<PAGE>   1
                                  EXHIBIT 10.3

                                                                        Concorde

                                    GUARANTY

         For good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, and to induce BNC Financial Corporation (the
"Lender"), at its option at any time or from time to time to make loans or
extend other accommodations to or for the account of Bayfront Ventures, a
Florida general partnership (the "Borrower"), the undersigned hereby absolutely
and unconditionally guarantee(s) to the Lender the full and prompt payment and
performance when due, whether at maturity or earlier by reason of acceleration
or otherwise, of each and every debt, liability and obligation of every type
which Borrower may now or at any time hereafter owe to the Lender, whether such
debt, liability or obligation now exists or is hereafter created or incurred,
and whether it is or may be direct or indirect, due or to become due, absolute
or contingent, primary or secondary, liquidated or unliquidated, or joint,
several or joint and several (all such debts, liabilities and obligations are
hereinafter collectively referred to as the "Indebtedness").

         The undersigned further acknowledges and agrees with the Lender that:

         1.       No act or thing need occur to establish the liability of the
undersigned hereunder, and no act or thing except full payment and discharge of
all Indebtedness shall in any way exonerate the undersigned or modify, reduce,
limit or release the liability of the undersigned hereunder.

         2.       This is an absolute, unconditional and continuing guaranty of
payment of the Indebtedness and shall continue to be in force and be binding
upon the undersigned until the Indebtedness is paid in full after the
termination of the Line of Credit, or until this guaranty is revoked as to
future transactions by written notice actually received by the Lender. Such
revocation shall not be effective as to Indebtedness existing or committed for
at the time of actual receipt of such notice by the Lender, or as to any
renewals, extensions and refinancings thereof. If there be more than one
guarantor hereunder, such revocation shall be effective only as to the one so
revoking. The dissolution or adjudication of bankruptcy of the undersigned shall
not revoke this guaranty, except upon actual receipt of written notice thereof
by the Lender and only prospectively, as to future transactions, as herein set
forth.

         3.       The undersigned represents and warrants to the Lender that: 
(a) the undersigned is a corporation duly organized and existing in good
standing and has full power and authority to make and deliver this guaranty; (b)
the execution, delivery and performance of this guaranty by the undersigned have
been duly authorized by all necessary action of its directors and shareholders
and do not and will not violate the provisions of, or constitute a default
under, any presently applicable law or its articles of incorporation or bylaws
or any agreement presently binding on it; (c) this guaranty has been duly
executed and delivered by the authorized officers of the undersigned and
constitutes its lawful, binding and legally enforceable obligation; (d) the
authorization, execution, delivery and performance of this guaranty do not
require notification to, registration with, or consent or approval by, any
federal, state or local regulatory body or administrative agency; (e) the
undersigned's preliminary audited financial statements dated September 30, 1997
and internally prepared interim financial statements dated January 31, 1998,
copies of which have been furnished to the Lender, have been prepared in
accordance with the generally accepted accounting principles consistently
applied with those of the preceding fiscal year (such consistently applied
accounting principles being "GAAP") and present fairly the financial condition
of the undersigned as of such dates and the result of its operations for the
periods then ended; (g) since September 30, 1997, neither the condition
(financial or otherwise), the business, the properties nor the operations of the
undersigned has been materially and adversely affected in any way; (h) the
undersigned has filed all Federal and State income and other tax returns which
are required to be filed, and has paid all taxes as shown on said returns and
all assessments received by the undersigned to the extent that such taxes have
become due; (i) the undersigned possesses adequate licenses, permits,
franchises, patents, copyrights, trademarks and trade names, or rights thereto,
to conduct its business substantially as now conducted and as presently proposed
to be conducted; (j) the

<PAGE>   2

undersigned is not in default of a material provision under any material
agreement, instrument, decree or order to which it is a party or by which it or
its property is bound or affected; (k) the undersigned has good title to all of
its properties and assets, including, without limitation, the collateral for the
Loan, free and clear of all mortgages, security interests, liens and
encumbrances, except as permitted by Section 6(f); (l) the undersigned
reasonably believes that the Year 2000 Problem will not result in a material
adverse change in the undersigned's business, condition (financial or
otherwise), operations, properties or prospects, or ability to repay the
Indebtedness; and (m) the undersigned is a citizen of the United States within
the meaning of the Ship Mortgage Act and 46 C.F.R. ss. 67.39 in that: (A) it is
incorporated under the laws of the State of Colorado ; (B) its chief executive
officer, by whatever title, is a citizen, (C) its chairman of the board of
directors is a citizen; (D) no more of its directors are non-citizens than a
minority of the number necessary to constitute a quorum; and (E) at least 75% of
the stock interest in the undersigned is owned by citizens.

         4.       The liability of the undersigned hereunder shall be limited to
the Indebtedness.

         5.       The undersigned hereby waives any right of contribution,
reimbursement, recourse or subrogation available to the undersigned against any
person liable to payment of the Indebtedness, or as to any collateral security
therefor; provided, however, that such waiver shall terminate on the 366th day
following the payment in full of the Indebtedness after the termination of any
commitment on part of the Lender to extend additional credit to the Borrower if,
and only so long as, no bankruptcy or reorganization proceedings have been
commenced by or against the Borrower under the United States Bankruptcy Code, 11
U.S.C. ss. 101, et seq. during the one year period following such payment date.

         6.       So long as the Indebtedness remains unpaid or the Line of
Credit is available to Borrower, the undersigned agrees:

         (a)      to furnish to the Lender:

                  (i)      as soon as available and in any event within 90 days
                           after the end of each of the undersigned's fiscal
                           years (or April 30, 1998, with respect to the
                           undersigned's 1997 fiscal year), a copy of the
                           undersigned's audited annual report, including
                           balance sheet and related statements of earnings,
                           stockholders' equity and cash flows for such fiscal
                           year, with comparative figures for the preceding
                           fiscal year, prepared in accordance with generally
                           accepted accounting principles consistently applied
                           (such consistently applied accounting principles
                           being "GAAP") and certified without qualification or
                           exception (other than a going-concern exception
                           arising solely from the lack of financing for the
                           Miami Princess) by the undersigned's current
                           independent public accountants or other independent
                           public accountants satisfactory to the Lender and
                           accompanied by the management letter, if any,
                           delivered by such independent public accountants to
                           the undersigned and the undersigned's response
                           thereto;

                  (ii)     as soon as available and in any event within 20 days
                           after the end of each month of the undersigned's
                           fiscal year, a copy of the undersigned' internally
                           prepared financial statements, consisting of a
                           balance sheet as of the close of such month and
                           related statements of earnings for such month and
                           from the beginning of such fiscal year to the end of
                           such month prepared in accordance with GAAP and
                           certified as accurate by the chief financial officer
                           or treasurer of the undersigned; and

                  (iii)    other financial or other information or certification
                           as the Lender may reasonably request;

         (b)      to maintain and preserve its corporate existence;
<PAGE>   3

         (c)      to file all federal and state tax income and other returns
                  (including, without limitation, withholding tax returns) which
                  are required and make payments as required of such taxes;
                  provided, however, that the undersigned shall not be required
                  to pay any such tax so long as the validity thereof is being
                  contested in good faith by appropriate proceedings and
                  adequate book reserves shall have been set aside with respect
                  thereto;

         (d)      to permit the Lender and its representatives at reasonable
                  times and intervals and upon reasonable notice to visit the
                  undersigned's offices and inspect the undersigned's books and
                  records and solely with respect to any examination made after
                  the occurrence and during the continuance of an Event of
                  Default, reimburse the Lender for all examination fees and
                  expenses incurred in connection with such examinations at its
                  then current rate for such services and for its out-of-pocket
                  expenses incurred in connection therewith;

         (e)      to maintain in full force and effect all of its material
                  rights, licenses, certifications, franchises and comply with
                  all applicable laws and regulations necessary to enable it to
                  conduct its business;

         (f)      not to create security interests or mortgages encumbering the
                  undersigned's assets except: (i) security interests in favor
                  of the Lender; (ii) other security interests described on
                  Schedule 6(f) attached hereto and incorporated herein by
                  reference; or (iii) security interests created in connection
                  with capitalized lease obligations or other purchase money
                  indebtedness but only to the extent that: (A) such security
                  interest attaches only to the assets then being acquired by
                  the undersigned, did not and does not attach to the
                  undersigned's current assets and does not secure any other
                  indebtedness; (B) no Default or Event of Default has occurred
                  and is continuing at the time of the proposed creation of such
                  security interest or would result therefrom; and (C) the
                  indebtedness intended to be secured by such security interest
                  is permitted by Section 6(g);

         (g)      not to create, incur, assume or suffer to exist any
                  indebtedness except: (i) the indebtedness under this guaranty
                  or any other Loan Document; (ii) current liabilities (other
                  than borrowed money) incurred in the ordinary course of
                  business; (iii) other indebtedness described in the January
                  31, 1998 balance sheet delivered to the Lender or on Schedule
                  6(g) attached hereto and incorporated herein by reference; or
                  (iv) capitalized lease obligations or purchase money
                  indebtedness incurred in connection with the acquisition of
                  equipment, but only to the extent that: (A) the aggregate
                  amount of such indebtedness does not exceed the lesser of: (1)
                  $250,000.00; or (2) the maximum amount of indebtedness which
                  the undersigned could then occur without violating Section
                  6(n) while maintaining its ability, after giving effect to the
                  indebtedness which the undersigned then proposes to incur,
                  additional indebtedness equal to the sum of the entire undrawn
                  amount of the Line of Credit plus $1.00; and (B) no Default or
                  Event of Default has occurred and is continuing at the time of
                  the proposed incurrence of such indebtedness or would result
                  therefrom;

         (h)      not to lease or sell all or any substantial portion of its
                  property and business to any other entity or entities, whether
                  in one transaction or a series of related transactions;

         (i)      not consolidate with or merge into or with any other entity or
                  entities;

         (j)      not to declare or pay any dividends or distributions,
                  purchase, redeem, retire or otherwise acquire for value any of
                  the undersigned's stock (or any warrant or option to purchase
                  any such partnership) now or hereafter outstanding, or return
                  any capital to its stockholders as such;
<PAGE>   4
         (k)      not to assume, guarantee, endorse or otherwise become liable
                  upon the obligation of any person, firm or corporation except
                  by endorsement of negotiable instruments for deposit or
                  collection in the ordinary course of business, nor sell any
                  notes or accounts receivable with or without recourse;

         (l)      engage in any business other than the businesses engaged in on
                  the date of this guaranty;

         (m)      not to change its United States citizenship as determined by
                  46 C.F.R. ss.67.39;

         (n)      maintain, at all times, its Net Worth at not less than
                  $2,000,000.00. "Net Worth means, at any date of determination,
                  the difference between: (i) the total assets appearing on the
                  undersigned's balance sheet at such date prepared in
                  accordance with GAAP, after deducting adequate reserves in
                  each case where, in accordance with GAAP, a reserve is proper;
                  and (b) the total liabilities (the "Total Liabilities")
                  appearing on such balance sheet where the Borrower's assets
                  and liabilities are consolidated with the undersigned's other
                  assets and liabilities; and/or

         (o)      permit, at any time, its ratio of Total Liabilities to Net
                  Worth to be more than 4 to 1;

         7.       The undersigned will pay or reimburse the Lender for all costs
and expenses (including reasonable attorneys' fees and legal expenses) incurred
by the Lender in connection with the protection, defense or enforcement of this
guaranty, whether or not suit is commenced, which attorneys' fees and legal
expenses shall include, but not be limited to, any attorneys' fees and legal
expenses incurred in connection with any appeal of a lower court's judgment or
order.

         8.       This guaranty is unsecured.

         9.       Whether or not any existing relationship between the
undersigned and Borrower has been changed or ended and whether or not this
guaranty has been revoked, the Lender may, but shall not be obligated to, enter
into transactions resulting in the creation or continuance of Indebtedness,
without any consent or approval by the undersigned and without any notice to the
undersigned. The liability of the undersigned shall not be affected or impaired
by any of the following acts or things: (i) any acceptance of collateral
security, guarantors, accommodation parties or sureties for any or all
Indebtedness; (ii) any one or more extensions or renewals of Indebtedness
(whether or not for longer than the original period) or any modification of the
interest rates, maturities or other contractual terms applicable to any
Indebtedness; (iii) any waiver or forbearance granted to Borrower, any delay or
lack of diligence in the enforcement of Indebtedness, or any failure to
institute proceedings, file a claim, give any required notices or otherwise
protect any Indebtedness; (iv) any full or partial release of, settlement with,
or agreement not to sue, Borrower or any other guarantor or other person liable
in respect of any Indebtedness; (v) any discharge of any evidence of
Indebtedness or the acceptance of any instrument in renewal thereof or
substitution therefor; (vi) any failure to obtain collateral security (including
rights of setoff) for Indebtedness, or to see to the proper or sufficient
creation and perfection thereof, or to establish the priority thereof, or to
protect, insure, or enforce any collateral security; or any modification,
substitution, discharge, impairment, or loss of any collateral security; (vii)
any foreclosure or enforcement of any collateral security; (viii) any transfer
of any Indebtedness or any evidence thereof; (ix) any order of application of
any payments or credits upon Indebtedness; (x) any election by the Lender under
ss. 1111(b)(2) of the United States Bankruptcy Code.

         10.      The undersigned waive(s) any and all defenses and claims of
Borrower, or any other obligor pertaining to Indebtedness, except the defense of
discharge by payment in full. Without limiting the generality of the foregoing,
the undersigned will not assert, plead or enforce against the Lender any defense
of waiver, release, discharge in bankruptcy, statute of limitations, res
judicata, statute of frauds, anti-deficiency statute, fraud, incapacity,
minority, usury, illegality or unenforceability which may be available to
Borrower or to any other person liable for any Indebtedness. The undersigned
expressly agree(s) that the undersigned shall be and remain liable for any
deficiency

<PAGE>   5

remaining after foreclosure of any mortgage or security interest securing
Indebtedness, whether or not the liability of Borrower or any other obligor for
such deficiency is discharged pursuant to statute or judicial decision.

         11.      The undersigned waive(s) presentment, demand for payment,
notice of dishonor or nonpayment and protest of any instrument evidencing
Indebtedness. The Lender shall not be required first to resort for payment of
the Indebtedness to Borrower or other persons or their properties or first to
enforce, realize upon or exhaust any collateral security for indebtedness,
before enforcing the guaranty.

         12.      If any payment applied by the Lender to Indebtedness is
thereafter set aside. recovered, rescinded or required to be returned for any
reason (including, without limitation, the bankruptcy, insolvency or
reorganization of Borrower or any other obligor), the Indebtedness to which such
payment was applied shall for the purposes of this guaranty be deemed to have
continued in existence, notwithstanding such application, and this guaranty
shall be enforceable as to such Indebtedness as fully as if such application had
never been made.

         13.      The undersigned acknowledges and agrees that the Lender (a)
has not made any representations or warranties with respect to, (b) does not
assume any responsibility to the undersigned for, and (c) has no duty to provide
information to the undersigned regarding, the enforceability of any of the
Indebtedness or the financial condition of the Borrower or any guarantor. The
undersigned has independently determined the creditworthiness of the Borrower
and the enforceability of the Indebtedness and until the Indebtedness is paid in
full will independently and without reliance on the Lender continue to make such
determinations.

         14.      The liability of the undersigned under this guaranty is in
addition to and shall be cumulative with all other liabilities of the
undersigned to the Lender as guarantor or otherwise, without any limitation as
to amount, unless the instrument or agreement evidencing or creating such other
liability specifically provides to the contrary.

         15.      This guaranty shall be enforceable against each person signing
this guaranty. If there be more than one signer of this guaranty or if there be
more than one guarantor of the Indebtedness, all agreements and promises herein
shall be construed to be joint and several with all other guarantors of the
Indebtedness, whether pursuant to this guaranty or separate guaranty and shall
be fully binding upon and enforceable against any or all of the undersigned and
the other guarantors. This guaranty shall be binding upon the undersigned and
the successors and assigns of the undersigned and shall inure to the benefit of
the Lender and its participants, successors and assigns. Any invalidity or
unenforceability of any provision or application of this guaranty shall not
affect other lawful provisions and application hereof, and to this end the
provisions of this guaranty are declared to be severable. This guaranty may not
be waived, modified, amended, terminated, released or otherwise changed except
by a writing signed by the undersigned and the Lender. This guaranty shall be
governed by the substantive laws (other than the law of conflicts) of the State
of Minnesota. The undersigned waive(s) notice of the Lender's acceptance hereof.

         16.      The undersigned hereby irrevocably submits to the jurisdiction
of any Minnesota state court or federal court over any action or proceeding
arising out of or relating to this guaranty, and the undersigned hereby
irrevocably agrees that all claims in respect of such action or proceeding may
be heard and determined in such Minnesota state or federal court. The
undersigned hereby irrevocably waives, to the fullest extent it may effectively
do so, the defense of an inconvenient forum to the maintenance of such action or
proceeding. The undersigned irrevocably consents to the service of copies of the
summons and complaints and any other process which may be served in any such
action or proceeding by the mailing by United States certified mail, return
receipt requested, of copies of such process to the undersigned's address shown
on the signature page. The undersigned agrees that a judgment final by appeal or
expiration of time to appeal without an appeal being taken in any such action or
proceeding shall be conclusive and may be enforced in any other jurisdictions by
suit on the judgment or in any other manner provided by law. Nothing in this
paragraph shall affect the right of the Lender to serve legal process in any
other manner permitted by law or affect the right of the Lender to bring any
action or proceeding against the undersigned or its property in the courts of
any other jurisdiction.
<PAGE>   6

         17.      Wherever possible, each provision of this guaranty shall be
interpreted in such manner as to be effective and valid under applicable law,
but if any provision of this guaranty shall be prohibited by or invalid under
such law, such provision shall be ineffective to the extent of such prohibition
or invalidity, without invalidating the remainder of such provision or the
remaining provisions of this guaranty. In any action or proceeding involving any
state corporate law, or any state or federal bankruptcy, insolvency,
reorganization or other law affecting the rights of creditors generally, if the
obligations of the undersigned hereunder would otherwise be held or determined
to be void, invalid or unenforceable on account of the amount of the
undersigned's liability under this guaranty, then, notwithstanding any other
provision of this guaranty to the contrary, the amount of such liability shall,
without any further action by the undersigned, the Lender or any other person,
be automatically limited and reduced to the highest amount which is valid and
enforceable as determined in such action or proceeding.

         18.      THE UNDERSIGNED HEREBY EXPRESSLY WAIVE(S) ANY RIGHT TO A TRIAL
BY JURY IN ANY ACTION OR PROCEEDING TO ENFORCE OR DEFEND ANY RIGHTS (a) UNDER
THIS GUARANTY OR UNDER ANY AMENDMENT, INSTRUMENT, DOCUMENT OR AGREEMENT
DELIVERED OR WHICH MAY IN THE FUTURE BE DELIVERED IN CONNECTION HEREWITH, OR (b)
ARISING FROM ANY RELATIONSHIP EXISTING IN CONNECTION WITH THIS GUARANTY, AND
AGREE(S) THAT ANY SUCH ACTION OR PROCEEDING SHALL BE TRIED BEFORE A COURT AND
NOT BEFORE A JURY.


                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]
<PAGE>   7
         IN WITNESS WHEREOF, this guaranty has been duly executed by the
undersigned this 17th day of March, 1998.

                                       Concorde Gaming Corporation

                                       By:  /s/ Jerry L. Baum
                                            ------------------------------------
                                       Its: President
                                            ------------------------------------

                                       Address: 3290 Lien Street
                                                Rapid City, SD 57709-0505
                                                Attention:_______________
                                                Telecopy No. (605) 342-0247

Subscribed and sworn to before me
this ____ day of March, 1998.



----------------------------------
Notary Public

<PAGE>   8
                                  Schedule 6(f)

                           Existing Security Interests

<PAGE>   9
                                  Schedule 6(g)

                              Existing Indebtedness