<PAGE>
 
                                                                    EXHIBIT 10.2

                              SUBSIDIARY GUARANTY
                              -------------------


     THIS SUBSIDIARY GUARANTY, dated as of December 30, 1996 (this "Guaranty"),
is made by CompUSA Holdings II Inc., a Delaware corporation, PCs Compleat, Inc.,
a Delaware corporation, CompUSA Holdings I Inc., a Delaware corporation,
CompTeam Inc., a Delaware corporation, CompUSA Management Company, a Delaware
business trust, CompUSA Stores L.P., a Texas limited partnership, and CompUSA
Holdings Company, a Delaware business trust (the "Guarantors"), of the
obligations of CompUSA Inc., a Delaware corporation ("Company"), under the
Credit Agreement (defined below) among the Company, NationsBank of Texas, N.A.
as Administrative Lender ("Administrative Lender"), and the lenders that are
parties to the Credit Agreement (singly, a "Lender" and collectively, the
"Lenders").


                                  BACKGROUND
                                  ----------

     1.   The Company, the Administrative Lender, and the Lenders have entered
into an Amended and Restated Credit Agreement, dated as of December 30, 1996
(said Credit Agreement, as it may hereafter be amended or otherwise modified
from time to time, being the "Credit Agreement").  The capitalized terms not
otherwise defined herein have the meanings specified in the Credit Agreement.

     2.   Pursuant to the Credit Agreement, the Company may, subject to the
terms of the Credit Agreement and the other Loan Documents, request that the
Lenders make Advances.

     3.   It is a requirement of Section 7.3(b) of the Credit Agreement that
each Guarantor guarantee repayment of the Obligations upon the terms and
conditions set forth herein.

     4.   The Board of Directors or regular trustees of either each Guarantor or
its general partner, as appropriate, has determined that the execution,
delivery, and performance of this Guaranty is necessary and convenient to the
conduct, promotion, and attainment of each such Guarantor's business.

     5.   The Guarantors desire to induce the Lenders to make such Advances,
which may reasonably be expected to benefit, directly or indirectly, each
Guarantor.

     NOW, THEREFORE, in consideration of the premises and in order to induce the
Lenders to make Advances under the Credit Agreement, the Guarantors hereby agree
as follows:

     1.   Guaranty.
          -------- 

          (a) Each Guarantor, jointly and severally, hereby unconditionally
     guarantees the punctual payment of, and promises to pay, when due, whether
     at stated maturity, by 
<PAGE>
 
     mandatory prepayment, by acceleration or otherwise, all obligations,
     indebtedness and liabilities, and all rearrangements, renewals and
     extensions of all or any part thereof, of the Company or any Subsidiary now
     or hereafter arising from, by virtue of or pursuant to the Credit
     Agreement, the Notes, any other Loan Document, and any and all renewals and
     extensions thereof, or any part thereof, or future amendments thereto,
     whether for principal, interest (including, without limitation, interest,
     fees and other charges that would accrue or become owing both prior to and
     subsequent to and but for the commencement of any proceeding against or
     with respect to the Company under any chapter of the Bankruptcy Code of
     1978, 11 U.S.C. (S)101 et seq. whether or not a claim is allowed for the
                            -- ---
     same in any such proceeding), premium, fees, commissions, expenses or
     otherwise (such obligations being the "Obligation"), and agrees to pay any
     and all reasonable expenses (including reasonable counsel fees and
     expenses) incurred in enforcement or collection of all or any part thereof,
     whether such obligations, indebtedness and liabilities are direct,
     indirect, fixed, contingent, joint, several or joint and several, and any
     rights under this Guaranty.

          (b) Anything contained in this Guaranty to the contrary
     notwithstanding, the obligations of each Guarantor hereunder shall be
     limited to a maximum aggregate amount equal to the largest amount that
     would not render its obligations hereunder subject to avoidance as a
     fraudulent transfer or conveyance under Section 548 of Title 11 of the
     United States Code or any applicable provisions of comparable state law
     (collectively, the "Fraudulent Transfer Laws"), in each case after giving
     effect to all other liabilities of such Guarantor, contingent or otherwise,
     that are relevant under the Fraudulent Transfer Laws (specifically
     excluding, however, any liabilities of such Guarantor in respect of
     intercompany indebtedness to the Company or other Affiliates of the Company
     to the extent that such indebtedness would be discharged in an amount equal
     to the amount paid by such Guarantor hereunder) and after giving effect as
     assets to the value (as determined under the applicable provisions of the
     Fraudulent Transfer Laws) of any rights to subrogation or contribution of
     such Guarantor pursuant to (i) Applicable Law or (ii) any agreement
     providing for an equitable allocation among such Guarantor and other
     Affiliates of the Company of obligations arising under guaranties by such
     parties (such limitation being the "Cap").

     2.   Guaranty Absolute.  The Guarantors guarantee that the Obligation will
          -----------------                                                    
be paid strictly in accordance with the terms of the Credit Agreement, the
Notes, and the other Loan Documents, regardless of any Applicable Law,
regulation or order now or hereafter in effect in any jurisdiction affecting any
of such terms or the rights of the Lender with respect thereto; provided,
however, nothing contained in this Guaranty shall require the Guarantors to make
any payment under this Guaranty in violation of any Applicable Law, regulation
or order now or hereafter in effect. The obligations and liabilities of each
Guarantor hereunder are independent of the obligations of the Company under the
Credit Agreement and any Applicable Law. The liability of each Guarantor under
this Guaranty shall be absolute and unconditional irrespective of:

                                      -2-
<PAGE>
 
          (a) the taking or accepting of any other security or guaranty for any
     or all of the Obligations, including any reduction or termination of any
     Commitment;

          (b) any increase, reduction or payment in full at any time or from
     time to time of any part of the Obligation;

          (c) any lack of validity or enforceability of the Credit Agreement,
     the Notes, or any other Loan Document or other agreement or instrument
     relating thereto, including but not limited by the unenforceability of all
     or any part of the Obligation by reason of the fact that (i) the
     Obligation, and/or the interest paid or payable with respect thereto,
     exceeds the amount permitted by Applicable Law, (ii) the act of creating
     the Obligation, or any part thereof, is ultra vires, (iii) the officers
                                             ----- -----                    
     creating same acted in excess of their authority, or (iv) for any other
     reason;

          (d) any lack of corporate power of the Company or any other Person at
     any time liable for the payment of any or all of the Obligation;

          (e) any insolvency, bankruptcy, reorganization, receivership or other
     proceeding under any applicable liquidation, conservatorship, bankruptcy,
     moratorium, arrangement, receivership, insolvency, reorganization, or
     similar laws from time to time in effect affecting the rights of creditors
     generally (collectively, "Debtor Relief Laws") involving the Company, any
     Guarantor or any other Person obligated on any of the Obligation;

          (f) any renewal, compromise, extension, acceleration or other change
     in the time, manner or place of payment of, or in any other term of, all or
     any of the Obligation; any adjustment, indulgence, forbearance, or
     compromise that may be granted or given by any Lender or the Administrative
     Lender to the Company, any Guarantor, or any Person at any time liable for
     the payment of any or all of the Obligation; or any other modification,
     amendment, or waiver of or any consent to departure from the Credit
     Agreement, the Notes, or any other Loan Document and other agreement or
     instrument relating thereto without notification of any Guarantor (the
     right to such notification being herein specifically waived by Guarantors);

          (g) any exchange, release, sale, subordination, or non-perfection of
     any collateral or Lien therein or any lack of validity or enforceability or
     change in priority, destruction, reduction, or loss or impairment of value
     of any collateral or Lien therein;

          (h) any release or amendment or waiver of or consent to departure from
     any other guaranty for all or any of the Obligation;

          (i) the failure by any Lender or the Administrative Lender to make any
     demand upon or to bring any legal, equitable, or other action against the
     Company or any other Person (including without limitation any other
     Guarantor), or the failure or 

                                      -3-
<PAGE>
 
     delay by any Lender or the Administrative Lender to, or the manner in which
     any Lender or the Administrative Lender shall, proceed to exhaust rights
     against any direct or indirect security for the Obligation;

          (j) the existence of any claim, defense, set-off, or other rights
     which the Company or any Guarantor may have at any time against the
     Company, the Lenders, or any Guarantor, or any other Person, whether in
     connection with this Guaranty, the Loan Documents, the transactions
     contemplated thereby, or any other transaction;

          (k) any failure of any Lender or the Administrative Lender to notify
     any Guarantor of any renewal, extension, or assignment of the Obligation or
     any part thereof, or the release of any security, or of any other action
     taken or refrained from being taken by any Lender or the Administrative
     Lender, it being understood that the Lenders and the Administrative Lender
     shall not be required to give any Guarantor any notice of any kind under
     any circumstances whatsoever with respect to or in connection with the
     Obligation;

          (l) any payment by the Company to the Lenders or the Administrative
     Lender is held to constitute a preference under any Debtor Relief Law or if
     for any other reason the Lenders or the Administrative Lender is required
     to refund such payment or pay the amount thereof to another Person; or

          (m) any other circumstance which might otherwise constitute a defense
     available to, or a discharge of, the Company, any Guarantor, any other
     guarantor or other Person liable on the Obligation, including without
     limitation any defense by reason of any disability or other defense of the
     Company, or the cessation from any cause whatsoever of the liability of the
     Company, or any claim that the Guarantors' obligations hereunder exceed or
     are more burdensome than those of the Company.

This Guaranty shall continue to be effective or be reinstated, as the case may
be, if at any time any payment of any of the Obligation is rescinded or must
otherwise be returned by any Lender or any other Person upon the insolvency,
bankruptcy or reorganization of the Company, any Guarantor or otherwise, all as
though such payment had not been made.

     3.   Waiver.  To the extent not prohibited by Applicable Law, each
          ------                                                       
Guarantor hereby waives: (a) promptness, protests, diligence, presentments,
acceptance, performance, demands for performance, notices of nonperformance,
notices of protests, notices of dishonor, notices of acceptance of this Guaranty
and of the existence, creation or incurrence of new or additional indebtedness,
and any of the events described in Section 2 and of any other occurrence or
matter with respect to any of the Obligation, this Guaranty or any of the other
Loan Documents; (b) any requirement that the Administrative Lender or any Lender
protect, secure, perfect, or insure any Lien or security interest or any
property subject thereto or exhaust any right or take any action against the
Company or any other Person or any collateral or pursue any other remedy in the
Administrative Lender's or any Lender's power whatsoever; (c) any right to
assert

                                      -4-
<PAGE>
 
against the Administrative Lender or any Lender as a counterclaim, set-off or
cross-claim, any counterclaim, set-off or claim which it may now or hereafter
have against the Company or other Person liable on the Obligation; (d) any right
to seek or enforce any remedy or right that the Administrative Lender or any
Lender now has or may hereafter have against the Company (to the extent
permitted by Applicable Law); (e) any right to participate in any collateral or
any right benefiting the Administrative Lender or the Lenders in respect of the
Obligation; and (f) any right by which it might be entitled to require suit on
an accrued right of action in respect of any of the Obligation or require suit
against the Company or any other Person, whether arising pursuant to Section
34.02 of the Texas Business and Commerce Code, as amended, Section 17.001 of the
Texas Civil Practice and Remedies Code, as amended, Rule 31 of the Texas Rules
of Civil Procedure, as amended, or otherwise.

     4.   Subrogation and Subordination.  Notwithstanding any reference to
          -----------------------------                                   
subrogation contained herein to the contrary, each Guarantor hereby irrevocably
waives any claim or other rights which it may have or hereafter acquire against
the Company that arise from the existence, payment, performance or enforcement
of such Guarantor's obligations under this Guaranty, including, without
limitation, any right of subrogation, reimbursement, exoneration, contribution,
indemnification, any right to participate in any claim or remedy of any Lender
against the Company or any collateral which any Lender now has or hereafter
acquires, whether or not such claim, remedy or right arises in equity, or under
contract, statutes or common law, including without limitation, the right to
take or receive from the Company, directly or indirectly, in cash or other
property or by set-off or in any other manner, payment or security on account of
such claim or other rights.  If any amount shall be paid to any Guarantor in
violation of the preceding sentence and the Obligations shall not have been paid
in full, such amount shall be deemed to have been paid to such Guarantor for the
benefit of, and held in trust for the benefit of, the Lenders, and shall
forthwith be paid to the Administrative Lender to be credited and applied upon
the Obligations, whether matured or unmatured, in accordance with the terms of
the Credit Agreement.  Each Guarantor acknowledges that it will receive direct
and indirect benefits from the financing arrangements contemplated by the Credit
Agreement and that the waiver set forth in this Paragraph 4 is knowingly made in
contemplation of such benefits.

     5.   Representations and Warranties.  Each Guarantor hereby represents and
          ------------------------------                                       
warrants that all representations and warranties as they apply to such Guarantor
only set forth in Article 4 of the Credit Agreement (each of which is hereby
incorporated by reference) is true and correct.

     6.   Covenants.  Each Guarantor hereby expressly assumes, confirms, and
          ---------                                                         
agrees to perform, observe, and be bound by all conditions and covenants set
forth in the Credit Agreement, to the extent applicable to it, as if it were a
signatory thereto.  Each Guarantor further covenants and agrees (a) punctually
and properly to perform all of such Guarantor's covenants and duties under any
other Loan Documents; (b) from time to time promptly to furnish the
Administrative Lender with any information or writings which the Administrative
Lender may request concerning this Guaranty; and (c) promptly to notify the
Administrative Lender of any claim, action, or proceeding affecting this
Guaranty.

                                      -5-
<PAGE>
 
     7.   Amendments, Etc.  No amendment or waiver of any provision of this
          ---------------                                                  
Guaranty nor consent to any departure by any Guarantor therefrom shall in any
event be effective unless the same shall be in writing and signed by the
Lenders, the Administrative Lender, or the Determining Lenders and then such
waiver or consent shall be effective only in the specific instance and for the
specific purpose for which given.

     8.   Addresses for Notices.  Unless otherwise provided herein, all notices,
          ---------------------                                                 
requests, consents and demands shall be in writing and shall be delivered by
hand or overnight courier service, mailed or sent by telecopy to the respective
addresses specified herein, or, as to any party, to such other addresses as may
be designated by it in written notice to all other parties.  All notices,
requests, consents and demands hereunder shall be deemed to have been given on
the date of receipt if delivered by hand or overnight courier service or sent by
telecopy, or if mailed, effective on the earlier of actual receipt or three (3)
days after being mailed by certified mail, return receipt requested, postage
prepaid, addressed as aforesaid.

     9.   No Waiver; Remedies.  No failure on the part of the Administrative
          -------------------                                               
Lender or any Lender to exercise, and no delay in exercising, any right
hereunder or under any of the Loan Documents shall operate as a waiver thereof;
nor shall any single or partial exercise of any right hereunder or under any of
the Loan Documents preclude any other or further exercise thereof or the
exercise of any other right.  Neither the Administrative Lender nor any Lender
shall be required to (a) prosecute collection or seek to enforce or resort to
any remedies against the Company or any other Person liable on any of the
Obligation, (b) join the Company or any other Person liable on any of the
Obligation in any action in which Lender prosecutes collection or seeks to
enforce or resort to any remedies against the Company or other Person liable on
any of the Obligation, or (c) seek to enforce or resort to any remedies with
respect to any Liens granted to (or benefiting, directly or indirectly) the
Administrative Lender or any Lender by the Company or any other Person liable on
any of the Obligation.  Neither the Administrative Lender nor any Lender shall
have any obligation to protect, secure or insure any of the Liens or the
properties or interests in properties subject thereto.  The remedies herein
provided are cumulative and not exclusive of any remedies provided by Applicable
Law.

     10.  Right of Set-off.  Upon the occurrence and during the continuance of
          ----------------                                                    
any Event of Default, each Lender is hereby authorized at any time and from time
to time, to the fullest extent permitted by Law, to set off and apply any and
all deposits (general or special, time or demand, provisional or final) at any
time held and other indebtedness at any time owing by such Lender to or for the
credit or the account of any Guarantor against any and all of the obligations of
any Guarantor now or hereafter existing under this Guaranty, irrespective of
whether or not such Lender shall have made any demand under this Guaranty. Each
Lender agrees promptly to notify such Guarantor after any such set-off and
application, provided that the failure to give such notice shall not affect the
validity of such set-off and application. The rights of each Lender under this
Section 10 are in addition to other rights and remedies (including, without
----------
limitation, other rights of set-off) which such Lender may have.

                                      -6-
<PAGE>
 
     11.  Liens.  To the extent not prohibited by Applicable Law, each Guarantor
          -----                                                                 
agrees that the Administrative Lender or any Lender, in its discretion, without
notice or demand and without affecting either the liability of such Guarantor,
the Company or any other Person liable on any of the Obligation under, or the
Liens and security interests created by, this Guaranty, or any security interest
or other Lien, may foreclose any deed of trust or mortgage or similar Lien
covering interests in real or personal property, and the interests in real or
personal property secured thereby, by nonjudicial sale; and such Guarantor
hereby waives any defense to the recovery by the Administrative Lender or any
Lender hereunder against the Company, such Guarantor or any collateral of any
deficiency after a nonjudicial sale and such Guarantor expressly waives any
defense or benefits that may be derived from Chapter 34 of the Texas Business
and Commerce Code, Section 51.003 of the Texas Property Code, or any similar
statute in effect in any other jurisdiction.  Without limiting the foregoing,
each Guarantor waives, to the extent not prohibited by Applicable Law,  any
defense arising out of any such nonjudicial sale even though such sale operates
to impair or extinguish any right of reimbursement or subrogation or any other
right or remedy of such Guarantor against the Company or any other Person or any
Collateral or any other collateral.  Each Guarantor hereby agrees that such
Guarantor shall be liable, subject to the limitations of Section 1 hereof, for
                                                         ---------            
any part of the Obligation remaining unpaid after any foreclosure.

     12.  Continuing Guaranty; Transfer of Notes.  This Guaranty is an
          --------------------------------------                      
irrevocable continuing guaranty of payment and shall (a) remain in full force
and effect until final payment in full after termination of the Commitments of
the Obligation and all other amounts payable under this Guaranty, (b) be binding
upon each Guarantor, its successors and assigns, and (c) inure to the benefit of
and be enforceable by each Lender and its successors, transferees and assigns.
Without limiting the generality of the foregoing clause (c), to the extent
permitted by the Credit Agreement, each Lender may assign or otherwise transfer
its rights under the Credit Agreement, the Notes or any of the Loan Documents or
any interest therein to any other Person, and such other Person shall thereupon
become vested with all the rights or any interest therein, as appropriate, in
respect thereof granted to the Lender herein or otherwise.

     13.  Information.  Each Guarantor acknowledges and agrees that it shall
          -----------                                                       
have the sole responsibility for obtaining from the Company such information
concerning the Company's financial condition or business operations as such
Guarantor may require, and that neither the Administrative Lender nor any Lender
has any duty at any time to disclose to any Guarantor any information relating
to the business operations or financial condition of the Company.

     14.  GOVERNING LAW.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
          -------------                                                       
ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS AND THE UNITED STATES OF AMERICA.
WITHOUT EXCLUDING ANY OTHER JURISDICTION, EACH GUARANTOR AGREES THAT THE STATE
AND FEDERAL COURTS OF TEXAS LOCATED IN DALLAS, TEXAS, SHALL HAVE JURISDICTION
OVER PROCEEDINGS IN CONNECTION HEREWITH.

                                      -7-
<PAGE>
 
     15.  WAIVER OF JURY TRIAL.  EACH GUARANTOR, THE ADMINISTRATIVE LENDER, AND
          --------------------                                                 
THE LENDERS HEREBY KNOWINGLY, VOLUNTARILY, IRREVOCABLY AND INTENTIONALLY WAIVE,
TO THE MAXIMUM EXTENT PERMITTED BY LAW, ALL RIGHT TO TRIAL BY JURY IN ANY
ACTION, PROCEEDING OR CLAIM ARISING OUT OF OR RELATED TO THIS AGREEMENT OR ANY
OF THE LOAN DOCUMENTS OR THE TRANSACTIONS CONTEMPLATED THEREBY.  THIS PROVISION
IS A MATERIAL INDUCEMENT TO EACH LENDER ENTERING INTO THE CREDIT AGREEMENT.

     16.  Ratable Benefit.  This Guaranty is for the ratable benefit of the
          ---------------                                                  
Lenders, each of which shall share any proceeds of this Guaranty pursuant to the
terms of the Credit Agreement.

     17.  Guarantor Insolvency.  Should any Guarantor become insolvent, fail to
          --------------------                                                 
pay its debts generally as they become due, voluntarily seek, consent to, or
acquiesce in the benefits of any Debtor Relief Law or become a party to or be
made the subject of any proceeding provided for by any Debtor Relief Law (other
than as a creditor or claimant) that could suspend or otherwise adversely affect
the rights of any Lender granted hereunder, then, the obligations of such
Guarantor under this Guaranty shall be, as between such Guarantor and such
Lender, a fully-matured, due, and payable obligation of such Guarantor to such
Lender (without regard to whether the Company is then in default under the
Credit Agreement or whether any part of the Obligation is then due and owing by
the Company to such Lender), payable in full by such Guarantor to such Lender
upon demand, which shall be the estimated amount owing in respect of the
contingent claim created hereunder.

     18.  Severability.  Any provision of this Guaranty which is for any reason
          ------------                                                         
prohibited or found or held invalid or unenforceable by any court or
governmental agency shall be ineffective to the extent of such prohibition or
invalidity or unenforceability without invalidating the remaining provisions
hereof in such jurisdiction or affecting the validity or enforceability of such
provision in any other jurisdiction.

     19.  ENTIRE AGREEMENT.  THIS GUARANTY, TOGETHER WITH THE OTHER LOAN
          ----------------                                              
DOCUMENTS, REPRESENTS THE FINAL AGREEMENT AMONG THE PARTIES AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS
OF THE PARTIES HERETO.  THERE ARE NO UNWRITTEN ORAL AGREEMENTS AMONG THE
PARTIES.

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

                                      -8-
<PAGE>
 
     IN WITNESS WHEREOF, the Guarantors have caused this Guaranty to be duly
executed and delivered by their respective officers thereunto duly authorized as
of the date first above written.

                                    COMPUSA HOLDINGS II INC.



                                    By:  /s/ Mark R. Walker
                                         --------------------------
                                         Name: Mark R. Walker
                                              ---------------------
                                         Title: Vice President
                                               --------------------
Address for all Guarantors:

CompUSA Inc.
14951 North Dallas Parkway
Dallas, Texas 75240
Attention:  Mark R. Walker
            Senior Vice President and General Counsel

                                    COMPUSA HOLDINGS I INC.



                                    By:  /s/ Mark R. Walker
                                         --------------------------
                                         Name: Mark R. Walker
                                              ---------------------
                                         Title: Vice President
                                               --------------------

                                    PCs COMPLEAT, INC.



                                    By:  /s/ Mark R. Walker
                                         --------------------------
                                         Name: Mark R. Walker
                                              ---------------------
                                         Title: Vice President
                                               --------------------

                                    COMPTEAM INC.



                                    By:  /s/ Mark R. Walker
                                         --------------------------
                                         Name: Mark R. Walker
                                              ---------------------
                                         Title: Vice President
                                               --------------------

                                      -9-
<PAGE>
 
                                    COMPUSA MANAGEMENT COMPANY



                                    By:  /s/ Mark R. Walker
                                         --------------------------------------
                                         Name: Mark R. Walker
                                              ---------------------------------
                                         Title: Vice President
                                               --------------------------------

                                    COMPUSA STORES L.P.

                                    By:  COMPUSA INC., its general partner



                                         By:  /s/ Mark R. Walker
                                              ---------------------------------
                                              Name: Mark R. Walker
                                                   ----------------------------
                                              Title: S.R. Vice-President - 
                                                     Secretary
                                                    ---------------------------

                                    COMPUSA HOLDINGS COMPANY



                                    By:  /s/ Mark R. Walker
                                         --------------------------------------
                                         Name: Mark R. Walker
                                              ---------------------------------
                                         Title: Vice President
                                               --------------------------------

                                     -10-