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                                                                   EXHIBIT 10.27

                 AMENDED AND RESTATED LIMITED GUARANTY AGREEMENT

                      (Knowledge Universe Capital Co. LLC)

                                   WITNESSETH:

        WHEREAS, Nextera Enterprises, Inc., a Delaware corporation ("Company")
has entered into an Amended and Restated Credit Agreement dated March 29, 2002
(the "Amended and Restated Credit Agreement") with Fleet National Bank, a
national banking association, as agent (the "Agent") for itself as a lender and
the other lenders party thereto (the "Lenders"), and other instruments,
agreements and documents (as the same may be amended, modified, changed,
extended or renewed from time to time, the "Credit Documents"), providing,
subject to the terms and conditions thereof, for loans and other credit
accommodations to be made by the Agent and Lenders to the Company;

        WHEREAS, the undersigned guarantor (the "Guarantor") is an affiliate of
Company and has entered into transactions with the Company, such that the
Agent's and Lenders' agreement to provide loans and other credit accommodations
to the Company will benefit the Guarantor;

        WHEREAS, as a condition to Agent's and Lenders' entering into the
Amended and Restated Credit Agreement, Agent and Lenders have required that the
Guarantor guarantee the full and prompt payment and performance of all
obligations of the Company to Agent and Lenders under the Credit Documents,
subject to the limitations contained in Section 3 hereof;

        NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, and in consideration of any and all
loans, advances, and extensions of credit now or hereafter made or extended by
Agent and Lenders to, for the account of or on behalf of the Company, Guarantor
hereby agrees as follows. Capitalized terms not otherwise defined herein shall
have the meanings given in the Credit Documents.

        1. Guaranty. Subject to Section 3 hereof, Guarantor hereby and
unconditionally and absolutely guarantees to Agent and Lender the full and
prompt payment and performance by the Company of all Loans, liabilities,
indebtedness and all other obligations which the Company now or hereafter may
have to Agent and Lenders under any and all Credit Documents, whether now
existing or hereafter arising, direct or indirect, absolute or contingent,
matured or unmatured, liquidated or unliquidated, secured or unsecured
including, without limitation, the full and prompt payment when due of all
principal, interest, charges, fees, costs and expenses and all other sums which
the Company may now or hereafter owe to Agent and Lenders arising under the
Credit Documents (including, without limitation, any interest which accrues
after the commencement of any case, proceeding or other action relating to the
bankruptcy, insolvency or reorganization of Company, whether or not allowed or
allowable as a claim in any such case, proceeding or other action) and hereby
agrees to indemnify Agent and Lenders against any expenses they may incur as a
result of the enforcement or attempted enforcement by, or on behalf of, the
Agent and Lenders of any of their rights and remedies under the Credit Documents
(collectively, the "Credit Obligations").

        2. Guaranty Unconditional. Subject to Section 3 hereof, this Guaranty is
a continuing, unconditional and absolute guaranty of payment and performance.
The obligations of the Guarantor hereunder are primary, with no recourse
necessary by Agent or Lenders against the Company or any collateral given to
secure the Credit Obligations guaranteed hereby prior to proceeding against the
Guarantor hereunder. If for any reason any installment or any other sum or
indebtedness now or hereafter owing by the Company to Agent or Lenders shall not
be paid when due, Guarantor will forthwith pay such sum to Agent and Lenders,
without regard to any counterclaim, set-off, deduction or defense of any kind
which the Company or Guarantor may have or assert, and without abatement,
suspension, deferment or reduction on account of any occurrence whatsoever. The
Guarantor hereby waives notice of and consent to all of the provisions of the
Credit Documents, to any amendments thereof, to any actions taken thereunder,
and to the execution by the Company of the above-referenced Credit

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Documents and of any other agreements, documents and instruments now or
hereafter executed by the Company in connection therewith. The Guarantor further
waives the following: notice of incurring of indebtedness and obligations by the
Company; acceptance of this Guaranty by Agent and Lenders; presentment and
demand for payment, protest, notice of protest and notice of dishonor or
non-payment of any instrument evidencing the Credit Obligations; any right to
require suit against the Company or any other party before enforcing this
Guaranty; any right to have security applied before enforcing this Guaranty; all
rights and claims of subrogation, reimbursement, indemnity, contribution, and
like claims and rights as against the Company and each other guarantor to the
extent such rights and claims arise out of or in connection with the Credit
Obligations; all defenses which might constitute a legal or equitable discharge
of a surety or guarantor; and all other notices and demands otherwise required
by law which the Guarantor may lawfully waive. Guarantor agrees that in the
event this Guaranty is enforced by suit or otherwise, Guarantor will reimburse
Agent and Lenders upon demand for all expenses incurred in connection therewith,
including without limitation, reasonable attorneys' fees and expenses.

        3. Limitations.

        (a) Monetary Limitation. Notwithstanding anything to the contrary
contained herein, (i) the liability of the Guarantor hereunder shall be limited
to the lesser of: (a) the Credit Obligations; or (b) the sum of (x) Two Million
Five Hundred Thousand Dollars ($2,500,000), plus (y) all costs and expenses
(including reasonable attorneys' fees and disbursements) incurred by the Agent
or Lenders in connection with the enforcement of their rights and remedies under
this Guaranty; and

        (b) Time Limitation. Notwithstanding anything to the contrary contained
herein, Guarantor shall not be required to make any payment of any amounts owed
by Guarantor hereunder, and no demand, draw, presentment or other request for
payment shall be made under or against the Irrevocable Letter of Credit issued
in the form of Exhibit 7.1.1 to the Amended and Restated Credit Agreement in the
original face amount of $2,500,000 ("Guarantor L/C"), until one or more of the
following has occurred:

               (i) Agent has made demand upon Company (which demand shall be
made in accordance with Section 18 of the Amended and Restated Credit Agreement,
with a copy to Guarantor) to pay or perform obligations under the Amended and
Restated Credit Agreement, upon or following an Event of Default (as defined in
the Amended and Restated Credit Agreement), and sixty (60) days have elapsed; or

               (ii) there has occurred a financial covenant Default or Event of
Default, and sixty (60) days have elapsed since the earlier of the delivery or
scheduled delivery to Lenders or Agent of the Company's financial statements; or

               (iii) Company has failed to make any payment when due to Lenders
or Agent under the Amended and Restated Credit Agreement or the Credit Documents
(as defined in the Amended and Restated Credit Agreement), and thirty (30) days
have elapsed; or

               (iv) a Bankruptcy Default (as defined in the Amended and Restated
Credit Agreement), and sixty (60) days have elapsed; or

               (v) December 15, 2003.

        4. Subordination. Payment of all amounts now or hereafter owed to
Guarantor by Company in respect of this Guaranty are hereby subordinated in
right of payment to the indefeasible payment in full to Agent and Lenders of the
Credit Obligations and all such amounts and any collateral security therefor are
hereby assigned to Agent and Lenders as collateral security for the Credit
Obligations.

        5. Waiver. Guarantor's obligations hereunder shall not be released,
discharged, terminated or impaired in any manner whatsoever, irrespective of the
lack of any notice to or consent of the Guarantor, by any of the following: (a)
new agreements or obligations of the Company with or to Agent and Lenders; (b)
amendments, indulgences, extensions, modifications, renewals or waivers of
default as to any existing or future agreements or obligations of the Company or
third parties with or to Agent and Lenders, or extensions of credit by Agent and
Lenders to the Company; (c) adjustments, compromises or releases of any
obligations of the Company, Guarantor or other parties, including any other
guarantors, or exchanges, releases, dispositions or sales of any collateral
security of the Company, Guarantor or other

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parties, including any other guarantors; (d) invalidity, irregularity, defect,
or unenforceability, for any reason, of any provision of any of the Credit
Documents, or of any instrument or writing, or of any security or other
guaranty, or acts or omissions by Agent or Lenders or the Company; (e) failure
to perfect any lien securing the obligations of the Company, Guarantor or other
parties, including any other guarantors; (f) interruptions in the business
relations between Agent and Lenders and the Company; (g) voluntary or
involuntary bankruptcy (including a reorganization in bankruptcy) of the Company
or entry of an order for relief against or with respect to the Company under
Title 11 of the United States Code; (h) composition, extension, moratoria or
other forms of debtor relief granted to the Company pursuant to law presently in
force or hereafter enacted; (i) payment of any or all obligations and
indebtedness of the Company in the event such payment is invalidated or avoided
by a trustee, custodian or receiver of the Company; (j) the insolvency,
liquidation, or dissolution of the Company (whenever or however arising); and
(k) the reorganization, merger or consolidation of the Company into or with
another entity, corporate or otherwise, or the sale or disposition of all or
substantially all of the capital stock, business or assets of the Company to any
other person or party.

        In addition, Guarantor waives all rights and defenses that it may have
because the Credit Obligations are, or may become, secured by real property.
This means, among other things: (i) Agent and Lenders may collect from Guarantor
without first foreclosing on any real or personal property pledged by the
Company; (ii) if Agent and Lenders foreclose on any real property pledged by the
Company: (A) the amount of the Credit Obligations may be reduced by the price
for which that property is sold at the foreclosure sale, even if it is worth
more than the sale price and (B) Agent and Lenders may collect from Guarantor
even if Agent and Lenders, by foreclosing on the real property, has destroyed
any right Guarantor may have to collect from the Company. This is an
unconditional and irrevocable waiver of any rights and defenses that Guarantor
may have because the Credit Obligations are, or may become, secured by real
property.

        6. Rights Upon Default. For the purposes of this Guaranty and indemnity,
all sums owing to Agent and Lenders by the Company shall be deemed at Agent's
election to have become immediately due and payable if there shall occur an
Event of Default as defined in any of the Credit Documents and all applicable
cure periods shall have lapsed, and subject to the limitations set forth in
Section 3, hereof, the Guarantor shall thereupon promptly pay Agent and Lenders
the entire amount of said indebtedness and obligations of the Company, and Agent
and Lenders shall be entitled to take any action deemed necessary or advisable
to enforce this Guaranty, including, without limitation, the enjoining of any
breach or threatened breach of this paragraph. In addition, subject to Section 3
hereof, and not in substitution of the foregoing, the Agent (in its discretion
or at the request of the Lenders) may from time to time draw upon that certain
Irrevocable Letter of Credit issued in the form of Exhibit 7.1.1 to the Amended
and Restated Credit Agreement.

        7. Account Stated. The books and records of Agent showing the account
between Agent and Lenders and Company shall be admissible in evidence in any
action or proceeding against or involving Guarantor as prima facie proof of the
items therein set forth, and the statements of Agent rendered to Company, to the
extent to which no written objection is made within thirty (30) days from the
date of sending thereof to Company, shall be deemed conclusively correct and
constitute an account stated between Agent and Lenders and Company and be
binding on Guarantor.

        8. Reinstatement. If after receipt of any payment of, or proceeds of
collateral applied to the payment of, any of the Credit Obligations, Agent or
any Lender is required to surrender or return such payment or proceeds to any
Person for any reason, then the Credit Obligations intended to be satisfied by
such payment or proceeds shall be reinstated and continue and this Guarantee
shall continue in full force and effect as if such payment or proceeds had not
been received by Agent and Lenders. Guarantor shall be liable to pay to Agent
and Lenders, and does indemnify and hold Agent and Lenders harmless for the
amount of any payments or proceeds surrendered or returned. This Section 8 shall
remain effective notwithstanding any contrary action which may be taken by Agent
and Lenders in reliance upon such payment or proceeds. This Section 8 shall
survive the termination or revocation of this Guarantee.

        9. Representations. Guarantor warrants and represents that (a) this
Guaranty has been duly executed and delivered and does not contravene any law or
any agreement to which Guarantor is a party or by which it is bound, (b) the
Guarantor: (i) is a limited liability company duly organized, validly existing
and in good standing under the laws of its organization; (ii) has all requisite
corporate or other power, and has all material, governmental, licenses,
authorizations, consents and approvals necessary to

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own its assets and carry on its business as now being or as proposed to be
conducted, except to the extent that the failure to have any such license,
authorization, consent or approval would not reasonably be expected (either
individually or in the aggregate) to materially affect the condition of the
Guarantor; and (iii) is qualified to do business and is in good standing in all
jurisdictions in which the nature of the business conducted by it makes such a
qualification necessary and where failure so to qualify would not reasonably be
expected (either individually or in the aggregate) to materially affect the
condition of the Guarantor; and (c) after giving effect to this Guaranty and the
transactions contemplated by the Credit Documents (and after taking into account
all recoveries Agent and Lenders are likely to realize from the Company on the
Company's obligations to Agent and Lender): (i) the aggregate value of all of
the assets and properties of Guarantor, at a fair valuation, will be greater
than the total amount which Guarantor is likely to be actually required to pay
on claims, including contingent claims; (ii) the aggregate present fair saleable
value of Guarantor's assets will be greater than the amount that will be
required to pay Guarantor's probable liability on debts, including contingent
liabilities, as they become absolute and mature; (iii) Guarantor has (and has no
reason to believe that it will not have) sufficient capital for the conduct of
his business affairs; and (iv) Guarantor does not intend to incur, and does not
believe that it has incurred, debts beyond its ability to pay as they mature.

        10. Set off. Guarantor hereby grants to Agent and Lenders, a lien,
security interest and right of set off as security for all liabilities and
obligations to Agent and Lenders, whether now existing or hereafter arising,
upon and against all deposits, credits, collateral and property, now or
hereafter in the possession, custody, safe keeping or control of Agent and
Lenders or any entity under the control of Fleet Financial Group, Inc., or in
transit to any of them. Subject to Section 3 hereof, at any time, without demand
or notice, Agent and Lenders may set off the same or any part hereof and apply
the same to any liability or obligation of Company and any Guarantor even though
unmatured and regardless of the adequacy of any other collateral securing the
Credit Obligations. ANY AND ALL RIGHTS TO REQUIRE AGENT AND LENDERS TO EXERCISE
THEIR RIGHTS OR REMEDIES WITH RESPECT TO ANY OTHER COLLATERAL WHICH SECURES THE
CREDIT OBLIGATIONS, PRIOR TO EXERCISING ITS RIGHT OF SET OFF WITH RESPECT TO
SUCH DEPOSITS, CREDITS OR OTHER PROPERTY OF THE COMPANY OR ANY GUARANTOR, ARE
HEREBY KNOWINGLY, VOLUNTARILY AND IRREVOCABLY WAIVED.

        11. Governing Law. This Agreement shall take effect as a sealed
instrument and shall be governed by and construed in accordance with the laws of
the Commonwealth of Massachusetts (without giving effect to its conflict of laws
rules).

        12. Jurisdiction. Guarantor irrevocably submits to the non-exclusive
jurisdiction of any federal or state court sitting in the Commonwealth of
Massachusetts, over any suit, action or proceeding arising out of or relating to
this Agreement and agrees that such courts shall have exclusive jurisdiction
over any suit, action or proceeding against Agent and Lenders. Guarantor
irrevocably waives, to the fullest extent that it may do so under applicable
law, any objection it may have or hereafter have to the laying of the venue of
any such suit, action or proceeding brought in any such court and any claim that
the same has been brought in an inconvenient forum.

        13. Waiver of Counterclaims. Guarantor waives all rights to interpose
any claims, deductions, set-offs or counterclaims of any nature (other than
compulsory counterclaims) in any action or proceeding with respect to this
Agreement, the Credit Obligations, the Collateral or any matter arising
therefrom or relating hereto or thereto.

        14. WAIVER OF JURY TRIAL. GUARANTOR, AGENT, AND LENDERS MUTUALLY HEREBY
KNOWINGLY, VOLUNTARILY AND INTENTIONALLY WAIVE THE RIGHT TO A TRIAL BY JURY IN
RESPECT OF ANY CLAIM BASED HEREON, ARISING OUT OF, UNDER OR IN CONNECTION WITH
THIS AGREEMENT OR ANY OTHER CREDIT DOCUMENTS CONTEMPLATED TO BE EXECUTED
HEREWITH OR ANY COURSE OF CONDUCT, COURSE OF DEALINGS, STATEMENTS (WHETHER
VERBAL OR WRITTEN) OR ACTIONS OF ANY PARTY. THIS WAIVER CONSTITUTES A MATERIAL
INDUCEMENT FOR AGENT AND LENDERS TO ACCEPT THIS AGREEMENT. Guarantor hereby
certifies that neither Agent, nor any Lender nor any of their representatives,
agents or counsel has represented, expressly or otherwise, that Agent and
Lenders would not, in the event of any such suit, action or proceeding, seek to
enforce this waiver of right to trial by jury. Guarantor acknowledges that Agent
and Lenders have been induced to enter into this Agreement by, among other
things, this waiver. Guarantor acknowledges that it has read the provisions

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of this Agreement and in particular, this Section 14; has consulted legal
counsel; understands the right it is granting in this Section 14 in particular;
and makes the above waiver knowingly, voluntarily and intentionally.

        15. Agent and Lender's Election. To the extent the Guarantor's liability
hereunder is rendered void, invalid, avoidable, unenforceable, or subordinated
to the claims of other creditors in whole or in part, on account of the amount
of such liability under any applicable state or federal laws dealing with the
recovery or avoidance of so-called "fraudulent conveyances" or otherwise
affecting the rights of creditors generally, then, notwithstanding any other
provision hereof to the contrary, the Agent and Lenders may at any time or from
time to time elect to limit the Guarantor's liability hereunder, such that the
amount of such liability will be limited and reduced to the highest amount that
is valid, non-avoidable, enforceable, and not subordinated to the claims of
other creditors.

        16. Miscellaneous. This Guaranty and all terms and conditions hereof
shall be binding upon Guarantor, its successors and assigns, and shall inure to
the benefit of and shall be fully enforceable by Agent and Lenders and their
successors and assigns. Wherever the context so requires herein, the singular
number includes the plural, and the plural number includes the singular.

        IN WITNESS WHEREOF, Guarantor has executed this instrument under seal as
of this 29th day of March, 2002.

                                       KNOWLEDGE UNIVERSE CAPITAL CO. LLC

  /s/ Jim L. Banks                     By:   /s/ Stanley E. Maron
--------------------------------             --------------------------------
Witness                                      Name: Stanley E. Maron
                                             Title:   Secretary

                                       Address:  Maron & Sandler
                                                 Attn: Stan Maron
                                                 844 Moraga Drive
                                                 Los Angeles, CA  90049

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                                                                   EXHIBIT 10.28

          AMENDMENT TO AMENDED AND RESTATED LIMITED GUARANTY AGREEMENT

                      (Knowledge Universe Capital Co. LLC)

                                   WITNESSETH:

        Reference is made to the Amended and Restated Limited Guaranty Agreement
dated March 29, 2002 ("Limited Guaranty"). All capitalized terms used herein
shall have the meanings given to such terms in the Limited Guaranty.

        1. The Guarantor and Agent (on behalf of itself and the other Lenders)
hereby agree that Section 3(b)(v) of the Limited Guaranty shall be amended by
deleting the date "December 15, 2003" therein and by substituting the date
"January 2, 2004" in place thereof.

        2. The Guarantor and the Agent (on behalf of itself and the other
Lenders) hereby affirm, confirm and ratify all of the terms of the Limited
Guaranty, as amended hereby.

        IN WITNESS WHEREOF, the parties hereto have executed this instrument
under seal under Massachusetts law on this 18th day of April, 2002.

                                         KNOWLEDGE UNIVERSE CAPITAL CO. LLC

  /s/ Jim L. Banks                       By:   /s/ Stanley E. Maron
--------------------------------               --------------------------------
Witness Jim L. Banks                           Name: Stanley E. Maron
                                               Title:   Secretary

                                         FLEET NATIONAL BANK, as Agent

  /s/ Sean Driscoll                      By:   /s/ Michael F. O'Neill
--------------------------------               --------------------------------
Witness Sean Driscoll                          Name: Michael F. O'Neill
                                               Title:   Senior Workout Officer

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