Document:

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4.1

                       AMENDMENT NO. 1 TO RIGHTS AGREEMENT
                       -----------------------------------

     THIS FIRST AMENDMENT TO RIGHTS AGREEMENT (this "Amendment") is made as of
this 23rd day of January 2000, to the Rights Agreement, dated as of April 29,
1994 (the "Rights Agreement") by and between COMPUSA INC. a Delaware corporation
(the "Corporation"), and AMERICAN STOCK TRANSFER & TRUST COMPANY (formerly Bank
One, Texas, N.A.), as Rights Agent (the "Rights Agent").

     WHEREAS, the Corporation has entered into a Merger Agreement (as the same
may be amended from time to time, the "Merger Agreement") among Grupo Sanborns,
S.A. de C.V., a corporation organized under the laws of the United Mexican
States ("Parent"), TPC Acquisition Corp., a Delaware corporation and the
Corporation, providing for a tender offer and merger transaction (collectively,
the "Transaction") pursuant to which the Purchaser has offered to purchase all
of the outstanding shares of common stock, par value $.01 per share (the
"Shares"), of the Corporation;

     WHEREAS, pursuant to the terms of the Merger Agreement, the Corporation has
agreed to amend the Rights Agreement as set forth in this Amendment;

     WHEREAS, pursuant to Section 27 of the Rights Agreement, this Amendment may
be entered into by the Corporation and the Rights Agent without the approval of
any holder of the Rights (as defined therein) or of the Shares.

     NOW, THEREFORE, in consideration of the premises and the mutual agreements
herein set forth, the parties hereto agree as follows:

     1. Section 1(a) of the Rights Agreement is hereby amended by adding the
following sentence at the end thereof:

          "Notwithstanding anything in this Rights Agreement to the contrary,
neither Parent nor Purchaser shall be or become an Acquiring Person as a result
of (i) the execution of the Merger Agreement, (ii) the announcement or making of
the Offer (as defined in the Merger Agreement), (iii) the acquisition of the
Shares pursuant to the Offer and the consummation of the Merger (as defined in
the Merger Agreement) or (iv) as result of any of the transactions contemplated
by the Merger Agreement."

     2. Section 3(a) of the Rights Agreement is amended by adding the following
sentence at the end thereof:

          "Notwithstanding anything in this Rights Agreement to the contrary, a
Distribution Date shall not be deemed to have occurred as a result of (i) the
execution of the Merger Agreement, (ii) the announcement or making of the Offer
(as

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defined in the Merger Agreement), (iii) the acquisition of the Shares pursuant
to the Offer and the consummation of the Merger (as defined in the Merger
Agreement) or (iv) as a result of any of the transactions contemplated by the
Merger Agreement."

     3. Section 13 of the Rights Agreement is hereby amended to add the
following sentence at the end thereof:

          "Notwithstanding anything in the Rights Agreement to the contrary,
none of the following: (i) the execution of the Merger Agreement, (ii) the
announcement or making of the Offer (as defined in the Merger Agreement), (iii)
the acquisition of the Shares pursuant to the Offer and the consummation of the
Merger (as defined in the Merger Agreement) or (iv) the consummation of any of
the transactions contemplated by the Merger Agreement shall be a Section 13
Event nor shall any of such events cause the Rights to be adjusted or become
exercisable in accordance with Section 13 or otherwise."

     4. This Amendment shall be effective as of January 23, 2000. The Rights
Agreement, as amended by this Amendment, shall remain in full force and effect
in accordance with its terms.

     5. Capitalized terms used but not defined in this Amendment shall have the
respective meanings ascribed thereto in the Rights Agreement.

     6. This Amendment shall be governed by the laws of the State of Delaware
and for all purposes shall be construed in accordance with the laws of such
state applicable to contracts to be made and performed entirely within such
state. This Amendment may be executed in any number of counterparts, each of
such counterparts shall for all purposes be deemed to be an original, and all
such counterparts shall together constitute but one and the same instrument. If
any provision, covenant or restriction of this Amendment is held by a court of
competent jurisdiction or other authority to be invalid, illegal or
unenforceable, the remainder of the terms, provisions, covenants and
restrictions of this Amendment shall remain in full force and effect and shall
in no way be effected, impaired or invalidated.

     7. If any term, provision, covenant or restriction of this Amendment is
held by a court of competent jurisdiction or other authority to be invalid, void
or unenforceable, the remainder of the terms, provisions, covenants and
restrictions of this Amendment shall remain in full force and effect and shall
in no way be affected, impaired or invalidated.

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     IN WITNESS WHEREOF, the parties herein have caused this Agreement to be
duly executed and attested, all as of the date and year first above written.

                                        COMPUSA INC.

                                        By: /s/ James F. Halpin
                                            ------------------------------
                                            Name:  James F. Halpin
                                            Title: President and
                                                   Chief Executive Officer

                                        AMERICAN STOCK TRANSFER &
                                        TRUST COMPANY

                                        By: /s/ Herbert Lemmer
                                            ------------------------------
                                            Name:  Herbert Lemmer
                                            Title: Vice President

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                 MORGAN STANLEY DEAN WITTER SELECT EQUITY TRUST
             THE COMPETITIVE EDGE BEST IDEAS PORTFOLIO SERIES 2000-1
                            REFERENCE TRUST AGREEMENT

          This Reference Trust Agreement dated January 25, 2000 between DEAN
WITTER REYNOLDS INC., as Depositor, and The Bank of New York, as Trustee, sets
forth certain provisions in full and incorporates other provisions by reference
to the document entitled "Dean Witter Select Equity Trust, Trust Indenture and
Agreement" (the "Basic Agreement") dated September 30, 1993, as amended. Such
provisions as are incorporated by reference constitute a single instrument (the
"Indenture").

                                WITNESSETH THAT:
                                 ---------------

          In consideration of the premises and of the mutual agreements herein
contained, the Depositor and the Trustee agree as follows:

                                       I.

                     STANDARD TERMS AND CONDITIONS OF TRUST

          Subject to the provisions of Part II hereof, all the provisions
contained in the Basic Agreement are herein incorporated by reference in their
entirety and shall be deemed to be a part of this instrument as fully and to the
same extent as though said provisions had been set forth in full in this
instrument except that the Basic Agreement is hereby amended as follows:

                    A. The first sentence of Section 2.01 is amended to add the
               following language at the end of such sentence: "and/or cash (or
               a letter of credit in lieu of cash) with instructions to the
               Trustee to purchase one or more of such Securities which cash (or
               cash in an amount equal to the face amount of the letter of
               credit), to the extent not used by the Trustee to purchase such
               Securities within the 90-day period following the first deposit
               of Securities in the Trust, shall be distributed to Unit Holders
               on the Distribution Date next following such 90-day period or
               such earlier date as the Depositor and the Trustee determine".

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                    B. Section 2.03 is amended to add the following to the end
               of the first paragraph thereof. The number of Units may be
               increased through a split of the Units or decreased through a
               reverse split thereof, as directed by the Depositor, which
               revised number of Units shall be recorded by Trustee on its
               books.

                    C. The first sentence of Section 2.06 is amended to add the
               following language after "Securities"))": "and/or cash (or a
               letter of credit in lieu of cash) with instructions to the
               Trustee to purchase one or more Additional Securities which cash
               (or cash in an amount equal to the face amount of the letter of
               credit), to the extent not used by the Trustee to purchase such
               Additional Securities within the 90-day period following the
               first deposit of Securities in the Trust, shall be distributed to
               Unit Holders on the Distribution Date next following such 90-day
               period or such earlier date as the Depositor and the Trustee
               determine".

                    D. Article III, entitled "Administration of Trust", Section
               3.01 Initial Cost shall be amended as follows:

                    Section 3.01 Initial Cost shall be amended to substitute the
following language:

                    SECTION 3.01. INITIAL COST The costs of organizing the Trust
               and sale of the Trust Units shall, to the extent of the expenses
               reimbursable to the Depositor provided below, be borne by the
               Unit Holders, PROVIDED, HOWEVER, that, to the extent all of such
               costs are not borne by Unit Holders, the amount of such costs not
               borne by Unit Holders shall be borne by the Depositor and,
               PROVIDED FURTHER, HOWEVER, that the liability on the part of the
               Depositor under this section shall not include any fees or other
               expenses incurred in connection with the administration of the
               Trust subsequent to the deposit referred to in Section 2.01. Upon
               notification from the Depositor that the primary offering period
               is concluded, the Trustee shall withdraw from the Account or
               Accounts specified in the Prospectus or, if no Account is therein
               specified, from the Principal Account, and pay to the Depositor
               the Depositor's reimbursable expenses of organizing the Trust and
               sale of the Trust Units in an amount certified to the Trustee by
               the Depositor. If the balance of the Principal Account is
               insufficient to make such withdrawal, the Trustee shall, as
               di-

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               rected by the Depositor, sell Securities identified by the
               Depositor, or distribute to the Depositor Securities having a
               value, as determined under Section 4.01 as of the date of
               distribution, sufficient for such reimbursement. The
               reimbursement provided for in this section shall be for the
               account of the Unitholders of record at the conclusion of the
               primary offering period and shall not be reflected in the
               computation of the Unit Value prior thereto. As used herein, the
               Depositor's reimbursable expenses of organizing the Trust and
               sale of the Trust Units shall include the cost of the initial
               preparation and typesetting of the registration statement,
               prospectuses (including preliminary prospectuses), the indenture,
               and other documents relating to the Trust, SEC and state blue sky
               registration fees, the cost of the initial valuation of the
               portfolio and audit of the Trust, the initial fees and expenses
               of the Trustee, and legal and other out-of-pocket expenses
               related thereto, but not including the expenses incurred in the
               printing of preliminary prospectuses and prospectuses, expenses
               incurred in the preparation and printing of brochures and other
               advertising materials and any other selling expenses. Any cash
               which the Depositor has identified as to be used for
               reimbursement of expenses pursuant to this Section shall be
               reserved by the Trustee for such purpose and shall not be subject
               to distribution or, unless the Depositor otherwise directs, used
               for payment of redemptions in excess of the per-Unit amount
               allocable to Units tendered for redemption.

                    E. The third paragraph of Section 3.05 is hereby amended to
               add the following sentence after the first sentence thereof:
               "Depositor may direct the Trustee to invest the proceeds of any
               sale of Securities not required for the redemption of Units in
               eligible money market instruments selected by the Depositor which
               will include only negotiable certificates of deposit or time
               deposits of domestic banks which are members of the Federal
               Deposit Insurance Corporation and which have, together with their
               branches or subsidiaries, more than $2 billion in total assets,
               except that certificates of deposit or time deposits of smaller
               domestic banks may be held provided the deposit does not exceed
               the insurance coverage on the instrument (which currently is
               $100,000), and provided further that the Trust's aggregate
               holding of certificates of deposit or time deposits issued by the
               Trustee may not ex-

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               ceed the insurance coverage of such obligations and U.S. Treasury
               notes or bills (which shall be held until the maturity thereof)
               each of which matures prior to the earlier of the next following
               Distribution Date or 90 days after receipt, the principal thereof
               and interest thereon (to the extent such interest is not used to
               pay Trust expenses) to be distributed on the earlier of the 90th
               day after receipt or the next following Distribution Date."

                    F. The first sentence of each of Sections 3.10, 3.11 and
               3.12 is amended to insert the following language at the beginning
               of such sentence, "Except as otherwise provided in Section
               3.13,".

                    G. The following new Section 3.13 is added

                    Section 3.13. EXTRAORDINARY EVENT-SECURITY RETENTION AND
               VOTING. In the event the Trustee is notified of any action to be
               taken or proposed to be taken by holders of the securities held
               by the Trust in connection with any proposed merger,
               reorganization, spin-off, split-off or split-up by the issuer of
               stock or securities held in the Trust, the Trustee shall take
               such action or refrain from taking any action, as appropriate, so
               as to insure that the securities are voted as closely as possible
               in the same manner and in the same general proportion as are the
               securities held by owners other than the Trust. If stock or
               securities are received by the Trustee, with or without cash, as
               a result of any merger, reorganization, spin-off, split-off or
               split-up by the issuer of stock or securities held in the Trust,
               the Trustee at the direction of the Depositor may retain such
               stock or securities in the Trust. Neither the Depositor nor the
               Trustee shall be liable to any person for any action or failure
               to take action with respect to this section.

                    H. Section 1.01 is amended to add the following definition:
               (9) "Deferred Sales Charge" shall mean any deferred sales charge
               payable in accordance with the provisions of Section 3.14 hereof,
               as set forth in the prospectus for a Trust. Definitions following
               this definition (9) shall be renumbered.

                    I. Section 3.05 is hereby amended to add the following
               paragraph after the end thereof: On each Deferred Sales Charge
               payment date set forth in the prospectus for

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               a Trust, the Trustee shall pay the account created pursuant to
               Section 3.14 the amount of the Deferred Sales Charge payable on
               each such date as stated in the prospectus for a Trust. Such
               amount shall be withdrawn from the Principal Account from the
               amounts therein designated for such purpose.

                    J.  Section   3.06B(3)   shall  be  amended  by  adding  the
               following: "and any Deferred Sales Charge paid".

                    K. Section 3.08 shall be amended by adding the following at
               the end thereof: "In order to pay the Deferred Sales Charge, the
               Trustee shall sell or liquidate an amount of Securities at such
               time and from time to time and in such manner as the Depositor
               shall direct such that the proceeds of such sale or liquidation
               shall equal the amount required to be paid to the Depositor
               pursuant to the Deferred Sales Charge program as set forth in the
               prospectus for a Trust.

                    L. Section 3.14 shall be added as follows:

                    Section 3.14. Deferred Sales Charge. If the prospectus for a
               Trust specifies a Deferred Sales Charge, the Trustee shall, on
               the dates specified in and as permitted by the prospectus,
               withdraw from the Income Account if such account is designated in
               the prospectus as the source of the payments of the Deferred
               Sales Charge, or to the extent funds are not available in that
               account or if such account is not so designated, from the
               Principal Account, an amount per Unit specified in the prospectus
               and credit such amount to a special, non-Trust account maintained
               at the Trustee out of which the Deferred Sales Charge will be
               distributed to the Depositor. If the Income Account is not
               designated as the source of the Deferred Sales Charge payment or
               if the balances in the Income and Principal Accounts are
               insufficient to make any such withdrawal, the Trustee shall, as
               directed by the Depositor, either advance funds, if so agreed to
               by the Trustee, in an amount equal to the proposed withdrawal and
               be entitled to reimbursement of such advance upon the deposit of
               additional monies in the Income Account or the Principal Account,
               sell Securities and credit the proceeds thereof to such special
               Depositor's account or credit Securities in kind to such special
               Depositor's Account. Such directions shall identify the
               Securities, if any, to be

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                                      -6-

               sold or distributed in kind and shall contain, if the Trustee is
               directed by the Depositor to sell a Security, instructions as to
               execution of such sales. If a Unit Holder redeems Units prior to
               full payment of the Deferred Sales Charge, the Trustee shall, if
               so provided in the prospectus, on the Redemption Date, withhold
               from the Redemption Price payment to such Unit Holder an amount
               equal to the unpaid portion of the Deferred Sales Charge and
               distribute such amount to such special Depositor's account or, if
               the Depositor shall purchase such Unit pursuant to the terms of
               Section 5.02 hereof, the Depositor shall pay the Redemption Price
               for such Unit less the unpaid portion of the Deferred Sales
               Charge. The Depositor may at any time instruct the Trustee to
               distribute to the Depositor cash or Securities previously
               credited to the special Depositor's account.

                    M. The Distribution Agency Agreement is amended to be
               applicable to the Morgan Stanley Dean Witter Select Equity Trust,
               The Competitive Edge Best Ideas Portfolio series.

                    N. Reference to "Dean Witter Select Equity Trust" is
               replaced by "Morgan Stanley Dean Witter Select Equity Trust".

                                      II.

                      SPECIAL TERMS AND CONDITIONS OF TRUST

                  The following special terms and conditions are hereby agreed
to:

                  A. The Trust is denominated Morgan Stanley Dean Witter Select
Equity Trust The Competitive Edge Best Ideas Portfolio Series 2000-1 (the "Best
Ideas Trust").

                  B. The publicly traded stocks listed in Schedule A hereto are
those which, subject to the terms of this Indenture, have been or are to be
deposited in trust under this Indenture.

                  C. The term, "Depositor" shall mean Dean Witter Reynolds
Inc.

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                                      -7-

                  D. The aggregate number of Units referred to in Sections 2.03
and 9.01 of the Basic Agreement is 24,982 for the Best Ideas Trust.

                  E. A Unit is hereby declared initially equal to 1/24,982th
for the Best Ideas Trust.

                  F. The term "In-Kind Distribution Date" shall mean
April 5, 2001.

                  G. The term "Record Dates" shall mean September 1, 2000, and
April 26, 2001 and such other date as the Depositor may direct. (Such dates are
set forth for the purposes of distribution to Unit Holders. Trust expenses shall
be paid quarterly.)

                  H. The term "Distribution Dates shall mean September 15, 2000
and on or about May 3, 2001 and such other date as the Depositor may direct.
(Such dates are set forth for the purposes of distribution to Unit Holders.
Trust expenses shall be paid quarterly.)

                  I. The term "Termination Date" shall mean April 26, 2001.

                  J. The Depositor's Annual Portfolio Supervision Fee shall be
a maximum of $0.25 per 100 Units.

                  K. The Trustee's Annual Fee as defined in Section 6.04 of
the Indenture shall be $0.80 per 100 Units.

                  L. For a Unit Holder to receive an "in-kind" distribution
during the life of the Trust, such Unit Holder must tender at least 25,000 Units
for redemption. There is no minimum amount of Units that a Unit Holder must
tender in order to receive an "in-kind" distribution on the In-Kind Date or in
connection with a rollover.

                  M. The Indenture is amended to provide that the period
during which the Trustee shall liquidate the Trust Securities shall not exceed
14 business days commencing on the first business day following the In-Kind
Date.

               (Signatures and acknowledgments on separate pages)

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          The Schedule of Portfolio Securities in the prospectus included in
this Registration Statement is hereby incorporated by reference herein as
Schedule A hereto.

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