Exhibit #10.46

                      FIRST AMENDMENT TO PURCHASE AGREEMENT

         THIS  AMENDMENT,  made as of July 28, 2000, by and between FAIR,  ISAAC
AND COMPANY, INC., a Delaware corporation  ("Seller"),  and SAN RAFAEL CORPORATE
CENTER, LLC, a Delaware limited liability company ("Buyer"),

                              W I T N E S S E T H:

         Recital of Facts:

         Seller and EOP-San Rafael Corporate Center Investor, L.L.C., a Delaware
limited liability  company,  formerly known as San Rafael Corporate Center,  LLC
("EOP-SR"), entered into the Purchase Agreement (the "Purchase Agreement") dated
June 28, 2000. On July 28, 2000,  EOP-SR  assigned all of EOP-SR's  rights under
the Purchase  Agreement to Buyer and Buyer  assumed all of EOP-SR's  obligations
under the  Purchase  Agreement.  EOP-SR has no further  interest in the Purchase
Agreement.  Seller and Buyer will amend the  Purchase  Agreement as set forth in
this Amendment.

         NOW,  THEREFORE,  in  consideration of the covenants in this Amendment,
Seller and Buyer agree as follows:

         1. Amendment.  Effective as of the date of this Amendment, the Purchase
Agreement shall be amended as follows:

         (a) Section 7.1(d) of the Purchase Agreement is amended in its entirety
to read as follows:

                  (d) On or before  August 28, 2000,  Seller shall have received
          the  written  approval  from  PG&E of the form of the PG&E  Assignment
          required by  paragraph 9 of the  Amended  and  Restated  Environmental
          Agreement  (the "PG&E  Environmental  Indemnity")  dated May 15, 1998,
          between Lease Plan North America,  Inc., an Illinois corporation,  and
          PG&E  recorded  May 20,  1998,  as Document  No.  1998-0033515  in the
          Official Records of Marin County.

         (b) The  following  sentence  is added to the end of section 7.2 of the
Purchase Agreement:

                  If Buyer  terminates  this Agreement  pursuant to this section
                  7.2,  then  the  Deposit  and all  interest  thereon  shall be
                  returned to Buyer upon such termination of this Agreement.

         (c) Section 7.2(d) of the Purchase Agreement is amended in its entirety
to read as follows:


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                  (d) On or before  August 28, 2000,  Buyer shall have  received
         the  written  approval  from  PG&E of the form of the  PG&E  Assignment
         required by paragraph 9 of the PG&E Environmental Indemnity.

         2. Legal  Effect.  Except as amended by this  Amendment,  the  Purchase
Agreement is unchanged and, as so amended,  the Purchase  Agreement shall remain
in full force and effect.

         3. Counterparts.  This Amendment may be executed in counterparts,  each
of which shall be an  original,  but all of which shall  constitute  one and the
same Amendment.

         IN WITNESS WHEREOF, Seller and Buyer have executed this Amendment as of
the date first hereinabove written.


                                          FAIR, ISAAC AND COMPANY, INC., a
                                          Delaware corporation

                                          By ___________________________________

                                          Title ________________________________



                       [Signature of Buyer on next page.]


<PAGE>


                          SAN RAFAEL CORPORATE CENTER, LLC,
                          a Delaware limited liability company

                          By  WILSON/EQUITY OFFICE, LLC, a Delaware
                              limited liability company, Member

                                By  WILSON INVESTORS, LLC, a Delaware
                                    limited liability company, Member

                                     By
                                        ---------------------------------------
                                     Title
                                           ------------------------------------

                                By  EOPMC INVESTOR, L.L.C., a Delaware
                                    limited liability company, Member

                                     By  EQUITY OFFICE PROPERTIES
                                         MANAGEMENT CORP., a Delaware
                                         corporation, Manager

                                           By
                                              ---------------------------------
                                           Title
                                                 ------------------------------

                          By  EOP-SAN RAFAEL CORPORATE CENTER
                              INVESTOR, L.L.C., a Delaware limited
                              liability company, Member

                                By  EOP OPERATING LIMITED
                                    PARTNERSHIP, a Delaware limited
                                    partnership, Member

                                     By EQUITY OFFICE PROPERTIES
                                        TRUST, a Maryland real estate
                                        investment trust, its sole General
                                        Partner

                                           By
                                              ---------------------------------
                                           Title
                                                 ------------------------------


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