Exhibit — C

INSTALLMENT CASH PROMISSORY NOTE

$2,000,000.00 Washington, D.C.    January 4, 2008 

FOR VALUE RECEIVED, the undersigned, WidePoint Corporation (“Maker”), does
hereby promise to pay to the order of Jin Kang (“Holder”), the principal amount
of Two Million Dollars ($2,000,000.00), together with simple interest computed
on such principal amount from the date hereof on the unpaid principal balance at
the fixed annual rate of (i) seven percent (7.0%) from the date of this Note
through December 31, 2008, and (ii) ten percent (10.0%) from January 1, 2009
through the date of payment of this Note as provided in Section 1 below.

        1.       Payment Terms. The principal and interest amount outstanding
under this Note shall be paid by the Maker to the Holder in one (1) lump sum
payment on the earlier of either April 1, 2009 or the business day immediately
following the filing by the Maker of its Annual Report on Form 10-K for the year
ending on December 31, 2008, or as otherwise provided under the Purchase
Agreement (as defined in Section 7 hereof), with all amounts due or payable at
any time under this Note being subject to adjustment and offset as provided in
the Purchase Agreement. The Maker shall make all such payments to the order of
the Holder at 1163 Daleview Dr. McLean, VA 22102 (or such other address as may
be designated in writing by Holder to Maker, which writing may be in the form of
electronic mail).

        2.       Right to Prepayment. This Note may be prepaid in whole or in
part at any time, without premium or penalty, with interest to the date of
payment. If this Note is prepaid, there is to be no discount from the obligation
to pay the full principal balance due at the time of prepayment.

        3.       Fees and Expenses. Whenever an attorney is used to obtain
payment under, or to otherwise enforce, this Note or to enforce, declare, or
adjudicate any rights or obligations under this Note, whether by suit or by any
other means whatsoever, the costs and expenses thereof, including reasonable
attorneys’ fees and expenses, shall be payable by the non-prevailing party.

        4.       Events of Default. Each of the following shall constitute an
event of default (“Event of Default”) hereunder:

            (a)       If Maker fails to pay any installment of interest or
principal on this Note when due hereunder which failure continues for a period
of thirty (30) days after Maker’s receipt of written notice from the Holder.
Receipt shall be deemed to have occurred if written notice is personally
delivered to and signed for on behalf of the Maker or delivered certified first
class mail, postage prepaid, to the addresses and representatives identified in
Section 9.1 of the Purchase Agreement;

            (b)       If Maker shall admit in writing its inability to pay its
debts as they become due, file a petition in bankruptcy or make a petition to
take advantage of any insolvency act; make an assignment for the benefit of
creditors, commence a proceeding for the appointment of a receiver, trustee,
liquidator or conservator of all or any substantial part of its property; file a
petition or answer seeking reorganization or similar relief under the Federal
bankruptcy laws or any similar law or statute governing the relative rights of
debtors and creditors;

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            (c)       If any of the creditors of Maker shall file a petition in
bankruptcy against Maker or for reorganization of Maker pursuant to the Federal
bankruptcy laws or similar law or statute, and if such petition shall not be
discharged or dismissed within sixty (60) calendar days after the date on which
such petition was filed; and

            (d)       If Maker breaches any covenant contained in the Credit
Agreement (defined below) .

        In the event of the happening of any Event of Default, then the unpaid
principal of this Note, and interest thereon until payment, shall forthwith
become absolute and due and payable without any notice or demand whatsoever.

        This Note (a) may not be changed, waived, discharged, or terminated
except by an instrument in writing signed by each of the Maker and Holder, and
(b) shall inure to the benefit of and be enforceable by the Holder and the
Holder’s heirs, executors, administrators, and personal representatives.

        This Note shall be governed by and construed in accordance with the laws
of the Commonwealth of Virginia applicable to agreements made and to be
performed entirely within such State.

        5.        Subordination Provisions.

            (a)        Subordination of Liabilities. Maker, for itself, its
successors and assigns, covenant and agree, and Holder, by his acceptance of
this Note, likewise covenants and agrees, that the payment of the principal of,
interest on, and all other amounts owing in respect of, this Note (the
“Subordinated Indebtedness”) is hereby expressly subordinated, to the extent and
in the manner set forth below, to the prior payment in full in cash of all
Senior Indebtedness (as defined in Section 5(g) hereof). The provisions of this
Section 5 shall constitute a continuing offer to all persons or other entities
who, in reliance upon such provisions, become holders of, or continue to hold,
Senior Indebtedness, and such holders are made obligees hereunder the same as if
their names were written herein as such, and they and/or each of them may
proceed to enforce such provisions.

        (b)        Maker Not to Make Payments with Respect to Subordinated
Indebtedness in Certain Circumstances.

                (i)        Upon the maturity of any Senior Indebtedness
(including interest thereon or fees or any other amounts owing in respect
thereof), whether at stated maturity, by acceleration or otherwise, all
Obligations (as defined in Section 5(g) hereof) owing in respect of the Senior
Indebtedness shall first be paid in full in cash, before any payment, whether in
cash, property, securities or otherwise, is made on account of the Subordinated
Indebtedness.

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                (ii)        The Maker may not, directly or indirectly, make any
payment of any Subordinated Indebtedness and may not acquire any Subordinated
Indebtedness for cash or property until all Senior Indebtedness has been paid in
full in cash if any default or event of default under the Credit Agreement (as
defined in Section 5(g) hereof) or any other issue of Senior Indebtedness is
then in existence or would result therefrom. The Holder hereby agrees that, so
long as any such default or event of default in respect of any issue of Senior
Indebtedness exists, Holder will not sue for, or otherwise take any action to
enforce the Maker’s obligations to pay, amounts owing in respect of this Note.
The Holder understands and agrees that to the extent that Section 5(b)(i) or
this Section 5(b)(ii) prohibits the payment of any Subordinated Indebtedness,
such unpaid amount shall not constitute a payment default under this Note and
the Holder may not sue for, or otherwise take action to enforce the Maker’s
obligation to pay such amount, provided that such unpaid amount shall remain an
obligation of the Maker to the Holder pursuant to the terms of this Note.

                (iii)        In the event that notwithstanding the provisions of
the preceding Section 5(b)(i) or Section 5(b)(ii), the Maker (or any person on
behalf of the Maker) shall make any payment on account of the Subordinated
Indebtedness at a time when payment is not permitted by Section 5(b)(i) or
Section 5(b)(ii), such payment shall be held by the Holder , in trust for the
benefit of, and shall be paid forthwith over and delivered to, the holders of
Senior Indebtedness or their representative or the trustee under the indenture
or other agreement pursuant to which any instruments evidencing any Senior
Indebtedness may have been issued, as their respective interests may appear
(including by giving effect to any intercreditor or subordination arrangements
among such holders), for application pro rata to the payment of all Senior
Indebtedness remaining unpaid to the extent necessary to pay all Senior
Indebtedness in full in accordance with the terms of such Senior Indebtedness,
after giving effect to any concurrent payment or distribution to or for the
holders of Senior Indebtedness.

            (c)        Subordination to Prior Payment of All Senior Indebtedness
on Dissolution, Liquidation or Reorganization of Maker. Upon any distribution of
assets of the Maker or upon dissolution, winding up, liquidation or
reorganization of the Maker (whether in bankruptcy, insolvency or receivership
proceedings or upon an assignment for the benefit of creditors or otherwise):

                (i)        the holders of all Senior Indebtedness shall first be
entitled to receive payment in full in cash of all Senior Indebtedness
(including, without limitation, post-petition interest at the rate provided in
the documentation with respect to the Senior Indebtedness, whether or not such
post-petition interest is an allowed claim against the debtor in any bankruptcy
or similar proceeding) before the Holder is entitled to receive any payment of
any kind or character on account of the Subordinated Indebtedness;

                (ii)        any payment or distributions of assets of the Maker
of any kind or character, whether in cash, property or securities to which the
Holder would be entitled except for the provisions of this Section 5, shall be
paid by the liquidating trustee or agent or other person making such payment or
distribution, whether a trustee in bankruptcy, a receiver or liquidating trustee
or other trustee or agent, directly to the holders of Senior Indebtedness or
their representative or representatives, or to the trustee or trustees under any
indenture under which any instruments evidencing any such Senior Indebtedness
may have been issued as their respective interests may appear (including by
giving effect to any intercreditor or subordination arrangements among such
holders), to the extent necessary to make payment in full in cash of all Senior
Indebtedness remaining unpaid, after giving effect to any concurrent payment or
distribution to the holders of such Senior Indebtedness; and

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                (iii)        in the event that, notwithstanding the foregoing
provisions of this Section 5(c), any payment or distribution of assets of the
Maker of any kind or character, whether in cash, property or securities, shall
be received by the Holder on account of Subordinated Indebtedness before all
Senior Indebtedness is paid in full in cash, such payment or distribution shall
be received and held in trust for and shall be paid over to the holders of the
Senior Indebtedness remaining unpaid or unprovided for or their representative
or representatives, or to the trustee or trustees under any indenture under
which any instruments evidencing any of such Senior Indebtedness may have been
issued, as their respective interests may appear (including by giving effect to
any intercreditor or subordination arrangements among such holders) for
application to the payment of such Senior Indebtedness until all such Senior
Indebtedness shall have been paid in full in cash, after giving effect to any
concurrent payment or distribution to the holders of such Senior Indebtedness.

            (d)        Subrogation. Subject to the prior payment in full in cash
of all Senior Indebtedness, the Holder shall be subrogated to the rights of the
holders of Senior Indebtedness to receive payments or distributions of assets of
the Maker applicable to the Senior Indebtedness until all amounts owing on this
Note shall be paid in full, and for the purpose of such subrogation no payments
or distributions to the holders of the Senior Indebtedness by or on behalf of
the Maker or by or on behalf of the Holder by virtue of this Section 5 which
otherwise would have been made to the Holder shall, as between the Maker and its
creditors other than the holders of Senior Indebtedness, and the Holder, be
deemed to be payment by the Maker to or on account of the Senior Indebtedness,
it being understood that the provisions of this Section 5 are and are intended
solely for the purpose of defining the relative rights of the Holder, on the one
hand, and the holders of the Senior Indebtedness, on the other hand.

            (e)        Obligation of the Maker Unconditional. Nothing contained
in this Section 5 or in this Note is intended to or shall impair, as between the
Maker, on one hand, and the Holder, on the other hand, the obligations of the
Maker, which are absolute and unconditional, to pay to the Holder the principal
of and interest on this Note as and when the same shall become due and payable
in accordance with their terms, or is intended to or shall affect the relative
rights of the Holder and creditors of the Maker other than the holders of the
Senior Indebtedness, nor shall anything herein or therein prevent the Holder
from exercising all remedies otherwise permitted by applicable law upon an event
of default under this Note, subject to the provisions of this Section 5 and the
rights, if any, under this Section 5 of the holders of Senior Indebtedness in
respect of cash, property, or securities of the Maker received upon the exercise
of any such remedy. Upon any distribution of assets of the Maker referred to in
this Section 5, the Holder shall be entitled to rely upon any order or decree
made by any court of competent jurisdiction in which such dissolution, winding
up, liquidation or reorganization proceedings are pending, or a certificate of
the liquidating trustee or agent or other person making any distribution to the
Holder, for the purpose of ascertaining the persons entitled to participate in
such distribution, the holders of the Senior Indebtedness and other indebtedness
of the Maker, the amount thereof or payable thereon, the amount or amounts paid
or distributed thereon and all other facts pertinent thereto or to this Section
5.

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            (f)        Subordination Rights Not Impaired by Acts or Omissions of
Maker or Holders of Senior Indebtedness. No right of any present or future
holders of any Senior Indebtedness to enforce subordination as herein provided
shall at any time in any way be prejudiced or impaired by any act or failure to
act on the part of the Maker or by any act or failure to act in good faith by
any such holder, or by any noncompliance by the Maker with the terms and
provisions of this Note, regardless of any knowledge thereof which any such
holder may have or be otherwise charged with. The holders of the Senior
Indebtedness may, without in any way affecting the obligations of the Holder
with respect hereto, at any time or from time to time and in their absolute
discretion, change the manner, place or terms of payment of, change or extend
the time of payment of, or renew, increase or otherwise alter, any Senior
Indebtedness or amend, modify or supplement any agreement or instrument
governing or evidencing such Senior Indebtedness or any other document referred
to therein, or exercise or refrain from exercising any other of their rights
under the Senior Indebtedness including, without limitation, the waiver of
default thereunder and the release of any collateral securing such Senior
Indebtedness, all without notice to or assent from the Holder.

            (g)        Senior Indebtedness. The term “Senior Indebtedness” shall
mean all Obligations (as defined below) (i) of the Maker under, or in respect
of, (x) the Credit Agreement, (as amended, modified, supplemented, extended,
restated, refinanced, replaced or refunded from time to time, the “Credit
Agreement”), dated as of January 2, 2008, by and among Maker, the various
lenders from time to time party thereto, including but not limited to Cardinal
Bank, and any renewal, extension, restatement, refinancing or refunding thereof,
and (y) each other Loan Document (as defined in the Credit Agreement) to which
the Maker is a party, (ii) of the Maker under, or in respect of (including by
reason of any guaranty to which the Maker is a party), any Hedge Agreement (as
defined in the Credit Agreement), and (iii) of the Maker under, or in respect of
(including by reason of any guaranty of) the Senior Notes and the Senior Note
Indenture (each as defined in the Credit Agreement). As used herein, the term
“Obligation” shall mean any principal, interest, premium, penalties, fees,
expenses, indemnities and other liabilities and obligations (including
guaranties of the foregoing liabilities and obligations) payable under the
documentation governing any Senior Indebtedness (including post-petition
interest at the rate provided in the documentation with respect to such Senior
Indebtedness, whether or not such interest is an allowed claim against the
debtor in any bankruptcy or similar proceeding).

            (h)       Retirement of Senior Indebtedness. Notwithstanding
anything contained in this Note to the contrary, the term “Senior Indebtedness”
shall also include and mean any new or future debt or other Obligation incurred
by the Maker to pay off or otherwise replace the Senior Indebtedness that
existed as of the date of this Note. Subject to the foregoing, in the event that
no Senior Indebtedness exists at any time in the future when any amount remains
outstanding and unpaid under this Note, then the indebtedness evidenced by this
Note shall no longer be subject to the subordination provisions of this Section
5. In addition to the foregoing, if the Maker satisfies the Senior Indebtedness
then simultaneously with such satisfaction and automatically and without any
further action on the part of the Maker and Holder the Holder shall be entitled
to all of the benefits provided for in the Senior Indebtedness including,
without limitation, having a first priority perfected security interest in all
of the assets of WidePoint, as if all of the terms and conditions of such Senior
Indebtedness will restated herein in their entirety.

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        6.       Assignment. This Note shall be binding upon the Maker and its
successors and assigns, including, without limitation, any person, firm or
corporation which may acquire substantially all of the Maker’s assets or
business or with or into which the Maker may be liquidated, consolidated, merged
or otherwise combined.

        7.       NOTE SUBJECT TO PURCHASE AGREEMENT. THE INDEBTEDNESS EVIDENCED
BY THIS NOTE IS SUBJECT TO THE TERMS OF THE MEMBERSHIP INTEREST PURCHASE
AGREEMENT, DATED AS OF JANUARY 2, 2008, BY AND BETWEEN THE MAKER, ISYS LLC, AND
THE HOLDER (the “Purchase Agreement”).

        8.       Approvals. The Maker shall comply with each of the covenants
contained in the Credit Agreement, The consent of the Holder shall be obtained
in those circumstances and to the same extent required in the Credit Agreement,
as if each of the covenants in the Credit Agreement was restated in their
entirety in this note, for so long as any amounts are due to the Holder by the
Maker under this Note. In the event any earnouts are achieved as defined in the
Purchase Agreement between the Holder and Maker, dated as of January 2, 2008,
while such earnout amounts have been earned and until they have been paid,
Holder shall have the same rights as stated in this Note.

        9.       Counterparts. This Note may be executed in one or more
counterparts, and by the different parties hereto in separate counterparts, each
of which when executed shall be deemed to be an original but all of which taken
together shall constitute one and the same Note.

        IN WITNESS WHEREOF, Maker has caused this Note to be executed by each of
its duly authorized officers.

Attest (Seal): WIDEPOINT CORPORATION

By:_______________________ By:______________________________       James
McCubbin       Steve Komar       Secretary       President