================================================================================

                                 UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549
                            _______________________

                                SCHEDULE 13D

                   Under the Securities Exchange Act of 1934
                               (Amendment No. 1)*


                                   IHS, INC.
                               (Name of Issuer)

                CLASS A COMMON STOCK, PAR VALUE $0.01 PER SHARE
                        (Title of Class of Securities)


                                   451734107
                                (CUSIP Number)

                               THOMAS J. MURPHY
                   C/O GENERAL ATLANTIC SERVICE COMPANY, LLC
                               3 PICKWICK PLAZA
                         GREENWICH, CONNECTICUT 06830
                           TEL. NO.: (203) 629-8600
                    (Name, Address and Telephone Number of
                     Person Authorized to Receive Notices
                              and Communications)
                            _______________________

                              SEPTEMBER 21, 2007
                     (Date of Event which Requires Filing
                              of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the  acquisition  which is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(e), 1(f) or 1(g), check the following box [ ].

Note:  Schedules filed in paper format shall include a signed original and five
copies of the schedule,  including  all  exhibits.  See Rule 13d-1(a) for other
parties to whom copies are to be sent.

*The remainder of this cover page shall be filled out for a reporting  person's
initial  filing on this form with respect to the subject  class of  securities,
and for any  subsequent  amendment  containing  information  which  would alter
disclosures provided in a prior cover page.

The  information  required  on the  remainder  of this  cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the  Securities  Exchange
Act of 1934 ("Act") or otherwise  subject to the liabilities of that section of
the Act but shall be subject to all other  provisions of the Act (however,  see
the Notes).

================================================================================


---------------------------                          ---------------------------
CUSIP NO. 451734107                                             Page 2 of 16
---------------------------                          ---------------------------

--------------------------------------------------------------------------------
         NAME OF REPORTING PERSON
1
         General Atlantic LLC
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP       (a)     [X]
                                                                (b)     [_]

--------------------------------------------------------------------------------
3        SEC USE ONLY


--------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         OO
--------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) or 2(e)

                                                                        [_]
--------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
--------------------------------------------------------------------------------
                                7     SOLE VOTING POWER

                                      -0-
                                ------------------------------------------------
                                8     SHARED VOTING POWER
          NUMBER OF
           SHARES                     4,687,500
     BENEFICIALLY OWNED         ------------------------------------------------
     BY EACH REPORTING           9    SOLE DISPOSITIVE POWER
           PERSON
            WITH                      -0-
                                ------------------------------------------------
                                10    SHARED DISPOSITIVE POWER

                                      4,687,500
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

         4,687,500
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                        [_]
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         10.5%
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         OO
--------------------------------------------------------------------------------


---------------------------                          ---------------------------
CUSIP NO. 451734107                                             Page 3 of 16
---------------------------                          ---------------------------

--------------------------------------------------------------------------------
         NAME OF REPORTING PERSON
1
         General Atlantic Partners 82, L.P.
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP       (a)     [X]
                                                                (b)     [_]

--------------------------------------------------------------------------------
3        SEC USE ONLY


--------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         OO
--------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) or 2(e)

                                                                        [_]
--------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
--------------------------------------------------------------------------------
                                7     SOLE VOTING POWER

                                      -0-
                                ------------------------------------------------
                                8     SHARED VOTING POWER
          NUMBER OF
           SHARES                     4,687,500
     BENEFICIALLY OWNED         ------------------------------------------------
     BY EACH REPORTING           9    SOLE DISPOSITIVE POWER
           PERSON
            WITH                      -0-
                                ------------------------------------------------
                                10    SHARED DISPOSITIVE POWER

                                      4,687,500
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

         4,687,500
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                        [_]
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         10.5%
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         PN
--------------------------------------------------------------------------------


---------------------------                          ---------------------------
CUSIP NO. 451734107                                             Page 4 of 16
---------------------------                          ---------------------------

--------------------------------------------------------------------------------
         NAME OF REPORTING PERSON
1
         GAP Coinvestments III, LLC
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP       (a)     [X]
                                                                (b)     [_]

--------------------------------------------------------------------------------
3        SEC USE ONLY


--------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         OO
--------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) or 2(e)

                                                                        [_]
--------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
--------------------------------------------------------------------------------
                                7     SOLE VOTING POWER

                                      -0-
                                ------------------------------------------------
                                8     SHARED VOTING POWER
          NUMBER OF
           SHARES                     4,687,500
     BENEFICIALLY OWNED         ------------------------------------------------
     BY EACH REPORTING           9    SOLE DISPOSITIVE POWER
           PERSON
            WITH                      -0-
                                ------------------------------------------------
                                10    SHARED DISPOSITIVE POWER

                                      4,687,500
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

         4,687,500
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                        [_]
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         10.5%
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         OO
--------------------------------------------------------------------------------


---------------------------                          ---------------------------
CUSIP NO. 451734107                                             Page 5 of 16
---------------------------                          ---------------------------

--------------------------------------------------------------------------------
         NAME OF REPORTING PERSON
1
         GAP Coinvestments IV, LLC
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP       (a)     [X]
                                                                (b)     [_]

--------------------------------------------------------------------------------
3        SEC USE ONLY


--------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         OO
--------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) or 2(e)

                                                                        [_]
--------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
--------------------------------------------------------------------------------
                                7     SOLE VOTING POWER

                                      -0-
                                ------------------------------------------------
                                8     SHARED VOTING POWER
          NUMBER OF
           SHARES                     4,687,500
     BENEFICIALLY OWNED         ------------------------------------------------
     BY EACH REPORTING           9    SOLE DISPOSITIVE POWER
           PERSON
            WITH                      -0-
                                ------------------------------------------------
                                10    SHARED DISPOSITIVE POWER

                                      4,687,500
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

         4,687,500
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                        [_]
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         10.5%
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         OO
--------------------------------------------------------------------------------


---------------------------                          ---------------------------
CUSIP NO. 451734107                                             Page 6 of 16
---------------------------                          ---------------------------

--------------------------------------------------------------------------------
         NAME OF REPORTING PERSON
1
         GAP-W, LLC
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP       (a)     [X]
                                                                (b)     [_]

--------------------------------------------------------------------------------
3        SEC USE ONLY


--------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         OO
--------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) or 2(e)

                                                                        [_]
--------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
--------------------------------------------------------------------------------
                                7     SOLE VOTING POWER

                                      -0-
                                ------------------------------------------------
                                8     SHARED VOTING POWER
          NUMBER OF
           SHARES                     4,687,500
     BENEFICIALLY OWNED         ------------------------------------------------
     BY EACH REPORTING           9    SOLE DISPOSITIVE POWER
           PERSON
            WITH                      -0-
                                ------------------------------------------------
                                10    SHARED DISPOSITIVE POWER

                                      4,687,500
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

         4,687,500
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                        [_]
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         10.5%
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         OO
--------------------------------------------------------------------------------


---------------------------                          ---------------------------
CUSIP NO. 451734107                                             Page 7 of 16
---------------------------                          ---------------------------

--------------------------------------------------------------------------------
         NAME OF REPORTING PERSON
1
         GapStar, LLC
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP       (a)     [X]
                                                                (b)     [_]

--------------------------------------------------------------------------------
3        SEC USE ONLY


--------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         OO
--------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) or 2(e)

                                                                        [_]
--------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
--------------------------------------------------------------------------------
                                7     SOLE VOTING POWER

                                      -0-
                                ------------------------------------------------
                                8     SHARED VOTING POWER
          NUMBER OF
           SHARES                     4,687,500
     BENEFICIALLY OWNED         ------------------------------------------------
     BY EACH REPORTING           9    SOLE DISPOSITIVE POWER
           PERSON
            WITH                      -0-
                                ------------------------------------------------
                                10    SHARED DISPOSITIVE POWER

                                      4,687,500
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

         4,687,500
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                        [_]
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         10.5%
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         OO
--------------------------------------------------------------------------------


---------------------------                          ---------------------------
CUSIP NO. 451734107                                             Page 8 of 16
---------------------------                          ---------------------------


ITEM 1.  SECURITY AND ISSUER.

                This   Amendment  No.  1  to  Schedule  13D  is  filed  by  the
undersigned  to amend the Schedule 13D, dated November 22, 2005, and relates to
the Class A Common Stock,  par value $0.01 per share (the "Common  Stock"),  of
IHS, Inc., a Delaware  corporation (the "Company").  This filing represents the
initial  Schedule 13D filing of GAP-W, LLC with regard to the Common Stock. The
address of the  principal  executive  office of the Company is 15 Inverness Way
East, Englewood, CO, 80112.


ITEM 2.  IDENTITY AND BACKGROUND.

ITEM 2 IS HEREBY AMENDED AND RESTATED IN ITS ENTIRETY AS FOLLOWS:

                This  statement  is being filed by a group,  as defined in Rule
13d-5 of the General Rules and  Regulations  promulgated  under the  Securities
Exchange Act of 1934, as amended (the "Exchange Act"). The members of the group
are General Atlantic LLC, a Delaware limited liability company ("GA"),  General
Atlantic  Partners 82, L.P., a Delaware  limited  partnership  ("GAP 82"),  GAP
Coinvestments III, LLC, a Delaware limited liability company ("GAPCO III"), GAP
Coinvestments  IV, LLC, a Delaware  limited  liability  company  ("GAPCO  IV"),
GAP-W, LLC, a Delaware limited liability company ("GAP-W"), and GapStar, LLC, a
Delaware limited  liability company  ("GapStar" and,  collectively with GA, GAP
82, GAPCO III,  GAPCO IV and GAP-W,  the  "Reporting  Persons").  The Reporting
Persons are located at 3 Pickwick Plaza, Greenwich,  Connecticut 06830. Each of
the  Reporting  Persons is engaged  in  acquiring,  holding  and  disposing  of
interests in various companies for investment purposes.


---------------------------                          ---------------------------
CUSIP NO. 451734107                                             Page 9 of 16
---------------------------                          ---------------------------


                GA is the general partner of GAP 82, the sole member of GapStar
and the manager of GAP-W.  The  Managing  Directors of GA are Steven A. Denning
(Chairman),  William E. Ford (Chief  Executive  Officer),  H. Raymond  Bingham,
Peter L. Bloom,  Mark F. Dzialga,  Klaus Esser,  Vince Feng,  William O. Grabe,
Abhay Havaldar, David C. Hodgson, Rene M. Kern, Jonathan Korngold,  Christopher
G.  Lanning,  Jeff Leng,  Anton J. Levy,  Marc F.  McMorris,  Thomas J. Murphy,
Matthew Nimetz, Ranjit Pandit, Andrew C. Pearson, David A. Rosenstein, Franchon
M.  Smithson,  Tom C. Tinsley,  Philip P.  Trahanas and Florian P.  Wendelstadt
(collectively,  the "GA Managing Directors").  Mr. Denning serves as a director
of the  Company.  The  Managing  Members  of GAPCO  III and GAPCO IV are the GA
Managing Directors.

                The  business  address  of  each of the GA  Managing  Directors
(other than Messrs.  Esser,  Feng,  Havaldar,  Bingham,  McMorris,  Tinsley and
Wendelstadt)  is General  Atlantic  Service  Company,  LLC,  3 Pickwick  Plaza,
Greenwich,  Connecticut  06830.  The  business  address of Mr. Esser is General
Atlantic  GmbH,  Koenigsallee  62, 40212,  Duesseldorf,  Germany.  The business
address of Messrs. Feng and Leng is General Atlantic Service Company, LLC, 18/F
One International  Finance Centre, 1 Harbour View Street,  Central,  Hong Kong.
The business address of Messrs. Havaldar and Pandit is General Atlantic Private
Limited,  151-152,  15th Floor, Maker Chamber VI, 220 Nariman Point, Mumbai 400
021,  India.  The business  address of Messrs.  Bingham and McMorris is General
Atlantic  Service  Company,  LLC, 228 Hamilton  Avenue,  Palo Alto,  California
94301. The business address of Mr. Tinsley is General Atlantic Service Company,
LLC, 2401 Pennsylvania Avenue N.W., Washington D.C. 20037. The business address
of Mr.  Wendelstadt is General Atlantic  Limited,  83 Pall Mall,  Fourth Floor,
London SW1Y 5ES, United Kingdom. Each of the GA Managing Directors,  other than
Messrs.  Esser,  Havaldar,  Leng and  Wendelstadt,  is a citizen  of the United
States.  Messrs.  Esser and Wendelstadt are citizens of Germany;  Mr. Kern is a
citizen of the United Staes and Germany;  Mr. Pandit is a citizen of the United
States and India;  Mr. Feng is a citizen of the United  States and Taiwan;  Mr.
Leng is a citizen of Hong Kong,  SAR;  and Mr.  Havaldar is a citizen of India.
The  present  principal  occupation  or  employment  of each of the GA Managing
Directors is as a Managing Director of GA.


---------------------------                          ---------------------------
CUSIP NO. 451734107                                            Page 10 of 16
---------------------------                          ---------------------------


                None of the  Reporting  Persons  and  none  of the  individuals
listed above has, during the last five years,  been (i) convicted in a criminal
proceeding  (excluding  traffic  violations or similar  misdemeanors) or (ii) a
party to a civil proceeding of a judicial or  administrative  body of competent
jurisdiction  or subject to any  judgment,  decree or final  order  finding any
violation of federal or state  securities laws or enjoining  future  violations
of, or prohibiting or mandating activities subject to, such laws.


ITEM 3.  SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

No change.


ITEM 4.  PURPOSE OF TRANSACTION.

No change.


ITEM 5.  INTEREST IN SECURITIES OF THE ISSUER.

ITEM 5 IS HEREBY AMENDED AND RESTATED IN ITS ENTIRETY AS FOLLOWS:

                (a)     As of the date hereof,  GA, GAP 82, GAPCO III, GAPCO IV
and GAP-W each own of record,  no shares of Common Stock,  3,307,917  shares of
Common Stock, 360,054 shares of Common Stock, 61,368 shares of Common Stock and
958,161 shares of Common Stock,  respectively,  representing  0.0%, 7.4%, 0.8%,
0.1% and 2.2% of the Company's  issued and outstanding  shares of Common Stock.
In addition,  GapStar has an indirect  ownership  interest in 87,891  shares of
Common  Stock  held  by  GAPCO  III,  representing  approximately  0.2%  of the
Company's issued and outstanding shares of Common Stock.  Percentages presented
in  response  to this  item are based on the  number of shares of Common  Stock
reported as issued and  outstanding in the Company's  Quarterly  Report on Form
10-Q filed on June 27, 2007.


---------------------------                          ---------------------------
CUSIP NO. 451734107                                            Page 11 of 16
---------------------------                          ---------------------------


                By virtue of the fact that (i) GA is the general partner of GAP
82, the sole member of GapStar  and the manager of GAP-W and (ii) the  Managing
Members  authorized and empowered to vote and dispose of the securities held by
GAPCO III and GAPCO IV are GA Managing Directors,  the Reporting Persons may be
deemed to share  voting  power and the power to direct the  disposition  of the
shares of Common Stock, which each owns of record. As of the date hereof,  each
of the  Reporting  Persons may be deemed to own  beneficially  an  aggregate of
4,687,500 shares of Common Stock, or 10.5% of the Common Stock.

                (b)     Each of the  Reporting  Persons has the shared power to
direct the vote and the shared power to direct the disposition of the 4,687,500
shares of Common Stock that may be deemed to be owned  beneficially  by each of
them.

                (c)     Except as set forth in this paragraph, to the knowledge
of the  Reporting  Persons  with  respect to the  persons  named in response to
paragraph  (a),  none of the persons  named in response  to  paragraph  (a) has
effected any transactions in shares of Common Stock during the past 60 days. On
September 21, 2007, 958,161 shares of Common Stock previously reported as owned
of record by GAP 82 were  transferred,  through  a series of  transactions,  to
GAP-W.

                (d)     No person  other  than the  persons  listed is known to
have the right to receive or the power to direct the receipt of dividends from,
or the  proceeds  from the sale of, any  securities  owned by any member of the
group.

                (e)     Not Applicable.



---------------------------                          ---------------------------
CUSIP NO. 451734107                                            Page 12 of 16
---------------------------                          ---------------------------


ITEM 6.  CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIP WITH RESPECT
         TO THE ISSUER.

No change.


ITEM 7.  MATERIALS TO BE FILED AS EXHIBITS.

              Exhibit 1:    Agreement   relating   to  the   filing   of  joint
                            acquisition   statements   as   required   by  Rule
                            13d-1(k)(1)  under the  Securities  Exchange Act of
                            1934, as amended.



---------------------------                          ---------------------------
CUSIP NO. 451734107                                            Page 13 of 16
---------------------------                          ---------------------------


                                   SIGNATURES

                After  reasonable  inquiry and to the best of my knowledge  and
belief,  I certify that the  information  set forth in this  statement is true,
complete and correct.

Dated:  September 28, 2007

                                        GENERAL ATLANTIC LLC


                                        By:  /s/ Thomas J. Murphy
                                             ---------------------------------
                                             Name:    Thomas J. Murphy
                                             Title:   Managing Director



                                        GENERAL ATLANTIC PARTNERS 82, L.P.

                                        By:  General Atlantic LLC,
                                             Its general partner


                                        By:  /s/ Thomas J. Murphy
                                             ---------------------------------
                                             Name:    Thomas J. Murphy
                                             Title:   Managing Director



                                        GAP COINVESTMENTS III, LLC


                                        By:  /s/ Thomas J. Murphy
                                             ---------------------------------
                                             Name:    Thomas J. Murphy
                                             Title:   A Managing Member




---------------------------                          ---------------------------
CUSIP NO. 451734107                                            Page 14 of 16
---------------------------                          ---------------------------



                                        GAP COINVESTMENTS IV, LLC


                                        By:  /s/ Thomas J. Murphy
                                             ---------------------------------
                                             Name:    Thomas J. Murphy
                                             Title:   A Managing Member



                                        GAP-W, LLC

                                        By:     General Atlantic LLC,
                                                Its manager


                                        By:  /s/ Thomas J. Murphy
                                             ---------------------------------
                                             Name:    Thomas J. Murphy
                                             Title:   Managing Director



                                        GAPSTAR, LLC
                                        By:  General Atlantic LLC,
                                             Its sole member


                                        By:  /s/ Thomas J. Murphy
                                             ---------------------------------
                                             Name:    Thomas J. Murphy
                                             Title:   Managing Director





---------------------------                          ---------------------------
CUSIP NO. 451734107                                            Page 15 of 16
---------------------------                          ---------------------------

         EXHIBIT 1
         to SCHEDULE 13D


                          JOINT ACQUISITION STATEMENT
                          PURSUANT TO RULE 13D-1(k)(1)

                The  undersigned  acknowledge  and  agree  that  the  foregoing
statement  on Schedule  13D is filed on behalf of each of the  undersigned  and
that all subsequent amendments to this statement on Schedule 13D shall be filed
on behalf of each of the undersigned without the necessity of filing additional
joint acquisition  statements.  The undersigned  acknowledge that each shall be
responsible for the timely filing of such amendments,  and for the completeness
and accuracy of the information concerning him, her or it contained herein, but
shall not be responsible for the  completeness  and accuracy of the information
concerning the other entities or persons,  except to the extent that he, she or
it knows or has reason to believe that such information is accurate.

Dated:  September 28, 2007

                                        GENERAL ATLANTIC LLC


                                        By:  /s/ Thomas J. Murphy
                                             ---------------------------------
                                             Name:    Thomas J. Murphy
                                             Title:   Managing Director



                                        GENERAL ATLANTIC PARTNERS 82, L.P.

                                        By:  General Atlantic LLC,
                                             Its general partner


                                        By:  /s/ Thomas J. Murphy
                                             ---------------------------------
                                             Name:    Thomas J. Murphy
                                             Title:   Managing Director



                                        GAP COINVESTMENTS III, LLC


                                        By:  /s/ Thomas J. Murphy
                                             ---------------------------------
                                             Name:    Thomas J. Murphy
                                             Title:   A Managing Member




---------------------------                          ---------------------------
CUSIP NO. 451734107                                            Page 16 of 16
---------------------------                          ---------------------------



                                        GAP COINVESTMENTS IV, LLC


                                        By:  /s/ Thomas J. Murphy
                                             ---------------------------------
                                             Name:    Thomas J. Murphy
                                             Title:   A Managing Member



                                        GAP-W, LLC

                                        By:  General Atlantic LLC,
                                             Its manager


                                        By:  /s/ Thomas J. Murphy
                                             ---------------------------------
                                             Name:    Thomas J. Murphy
                                             Title:   Managing Director



                                        GAPSTAR, LLC
                                        By:  General Atlantic LLC,
                                             Its sole member


                                        By:  /s/ Thomas J. Murphy
                                             ---------------------------------
                                             Name:    Thomas J. Murphy
                                             Title:   Managing Director