Document:

<PAGE>   1
                                                                    Exhibit 4.14

                        ASSIGNMENT AND SECURITY AGREEMENT
                           Dated as of March 30, 2000
                                       by
                            NRG POWER MARKETING INC.
                                       to
                           THE CHASE MANHATTAN BANK,
                              as Collateral Agent
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                                TABLE OF CONTENTS

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                                    ARTICLE I
                     DEFINITIONS; RULES OF INTERPRETATION ..................     2

SECTION 1.1.          Definitions ..........................................     2

SECTION 1.2.          Rules of Interpretation ..............................     3

                                   ARTICLE II
                  ASSIGNMENT AND GRANT OF SECURITY INTERESTS ...............     3

SECTION 2.1.          Assignment and Grant of Security Interest ............     3

SECTION 2.2.          Security Interest Absolute ...........................     5

SECTION 2.3.          Power of Attorney ....................................     6

SECTION 2.4.          Inspection and Verification ..........................     8

                                   ARTICLE III
              GENERAL REPRESENTATIONS, WARRANTIES AND COVENANTS ............     8

SECTION 3.1.          Title and Authority ..................................     9

SECTION 3.2.          Validity, Perfection and Priority of Lien ............     9

SECTION 3.3.          No Liens; Other Financing Statements .................     9

SECTION 3.4.          Chief Executive Office; Name; Records ................    10

SECTION 3.5.          Additional Statements and Schedules ..................    11

SECTION 3.6.          Further Actions ......................................    11

                                   ARTICLE IV
                         CASH PROCEEDS OF COLLATERAL .......................    11

                                    ARTICLE V
                          SPECIAL PROVISIONS CONCERNING
                              ASSIGNED REVENUES ............................    12

SECTION 5.1.          Additional Representations and Warranties ............    12

SECTION 5.2.          Maintenance of Records; Legending of Records .........    12

SECTION 5.3.          Modification of Terms; No Payment to Grantor .........    13

SECTION 5.4.          Collection ...........................................    13
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SECTION 5.5.          Instruments ..........................................    13

                                   ARTICLE VI
                       DUTY OF CARE OF COLLATERAL AGENT ....................    13

SECTION 6.1.          Collateral Agent's Duties; Reasonable Care ...........    13

SECTION 6.2.          Further Protection ...................................    14

                                   ARTICLE VII
                 REMEDIES UPON OCCURRENCE OF A TRIGGER EVENT ...............    14

SECTION 7.1.          Remedies; Obtaining the Power Marketing Security
                      Agreement Collateral upon Trigger Event ..............    14

SECTION 7.2.          Remedies; Disposition of the Power Marketing
                      Security Agreement Collateral ........................    15

SECTION 7.3.          Waiver ...............................................    16

SECTION 7.4.          Application of Proceeds; Grantor Liable for
                      Deficiency ...........................................    17

SECTION 7.5.          No Waiver; Remedies Cumulative .......................    17

SECTION 7.6.          Discontinuance of Proceedings ........................    18

                                  ARTICLE VIII
                                  MISCELLANEOUS ............................    18

SECTION 8.1.          Notices ..............................................    18

SECTION 8.2.          Amendment ............................................    18

SECTION 8.3.          Successors and Assigns ...............................    19

SECTION 8.4.          Survival .............................................    19

SECTION 8.5.          Headings Descriptive .................................    19

SECTION 8.6.          Severability .........................................    19

SECTION 8.7.          Grantor's Duties .....................................    19

SECTION 8.8.          Termination; Release .................................    19

SECTION 8.9.          Reinstatement ........................................    20

SECTION 8.10.         Counterparts .........................................    20

SECTION 8.11.         Governing Law; Submission to Jurisdiction;
                      Waiver of Jury Trial .................................    20

SECTION 8.12.         Authority of Collateral Agent ........................    21

SECTION 8.13.         Conflict with Intercreditor Agreement ................    22

SECTION 8.14.         Indemnities and Expenses .............................    22

SECTION 8.15.         Entire Agreement .....................................    22

SECTION 8.16.         Independent Security .................................    22
</TABLE>

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SECTION 8.17.         Third Party  Beneficiaries ...........................    23

SECTION 8.18.         Limitation  of  Liability ............................    23

SECTION  8.19.        Merger of  Collateral  Agent .........................    23
</TABLE>

Schedule I - Filing Offices

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                        ASSIGNMENT AND SECURITY AGREEMENT

                  ASSIGNMENT AND SECURITY AGREEMENT, dated as of March 30, 2000
(this "Agreement"), made by NRG Power Marketing, Inc., a Delaware corporation
(the "Grantor"), in favor of The Chase Manhattan Bank, as collateral agent
(together with its successors in such capacity, the "Collateral Agent") for the
benefit of the Secured Parties.

                              W I T N E S S E T H:

         WHEREAS, pursuant to the Acquisition Agreement, the Subsidiary
Guarantor, a wholly owned subsidiary of the Issuer, is acquiring the Project
from Cajun; and

         WHEREAS, the Issuer has simultaneously with the execution and delivery
of this Agreement issued and sold the Initial Bonds pursuant to the Indenture;
and

         WHEREAS, payments of the principal of, premium (if any), interest on
and any other amounts due with respect to the Initial Bonds will be serviced by
repayment of the Guarantor Loan and guaranteed (subject to certain limitations)
by the Subsidiary Guarantor; and

         WHEREAS, the Working Capital Facility Banks, the Working Capital
Facility Agent and the Issuer are parties to the Working Capital Facility
providing, subject to the terms and conditions thereof, for the making of loans
to the Issuer for working capital purposes; and

         WHEREAS, the Grantor is an Affiliate of the Issuer and Subsidiary
Guarantor and anticipates benefitting directly and indirectly from the issuance
and sale of the Initial Bonds and the entry by the Issuer into the Working
Capital Facility and therefore, is willing to secure the obligations of the
Issuer and the Subsidiary Guarantor under the Finance Documents by entering into
this Agreement with the Collateral Agent, pursuant to which the Collateral
Agent, acting on behalf of the Secured Parties, will obtain a continuing Lien on
and perfected security interest in, the Power Marketing Security Agreement
Collateral.

                  NOW THEREFORE, in consideration of the Secured Parties
entering into the Finance Documents and to induce the Secured Parties to release
the proceeds of the issuance and sale of the Initial Bonds, and for other good
and valuable consideration, the receipt and adequacy of which are hereby
acknowledged, the Grantor hereby agrees with the Collateral Agent as follows:
<PAGE>   6
                                    ARTICLE I
                      DEFINITIONS; RULES OF INTERPRETATION

                  SECTION 1.1.  Definitions.

                  (a) For all purposes of this Agreement, capitalized terms used
but not otherwise defined herein shall have the meanings set forth in Appendix A
to the Trust Indenture, dated as of March 30, 2000, among NRG South Central
Generating LLC, Louisiana Generating LLC and The Chase Manhattan Bank, as Bond
Trustee (the "Indenture").

                  (b) The following terms shall have the following respective
meanings unless the context otherwise requires. The definitions shall be equally
applicable to the singular and plural forms of the terms defined. Commercial
terms used herein but not defined herein or in Appendix A to the Indenture shall
have the meanings specified for such terms in the UCC as in effect in the State
of New York.

                  "Agreement" shall have the meaning specified in the preamble
hereto.

                  "Assigned Revenues" have the meaning specified in Section
2.1(a).

                  "Financing Statements" shall mean all financing statements,
recordings, filings or other instruments of registration necessary and
appropriate to perfect a security interest or lien by filing in any appropriate
filing or recording office in accordance with the UCC as enacted in any and all
relevant jurisdictions or any other relevant applicable law.

                  "Grantor" shall have the meaning specified in the preamble
hereto.

                  "Instruments" shall mean "instruments" as such term is defined
in the UCC as in effect in any relevant jurisdiction.

                  "Power Marketing Security Agreement Collateral" shall have the
 meaning specified in Section 2.1(a).

                  "Proceeds" shall mean "proceeds" as such term is defined in
the UCC as in effect in any relevant jurisdiction or under other relevant law
and, in any event, shall include, but shall not be limited to, (i) any and all
proceeds of any insurance, indemnity, warranty or guaranty payable to the
Collateral Agent or the Grantor from time to time, and claims for insurance,
indemnity, warranty or guaranty effected or held for the benefit of the Grantor
with

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respect to any of the Power Marketing Security Agreement Collateral, (ii) any
and all payments (in any form whatsoever) made or due and payable to the Grantor
from time to time in connection with any requisition, confiscation,
condemnation, seizure or forfeiture of all or any part of the Power Marketing
Security Agreement Collateral by any Governmental Authority (or any person
acting under color of Governmental Authority) and (iii) any and all other
amounts from time to time paid or payable under or in connection with any of the
Power Marketing Security Agreement Collateral.

                  "Security Interest" shall have the meaning specified in
Section 2.1(a).

                  "UCC" shall mean the Uniform Commercial Code as in effect from
time to time in the State of New York; provided that, if by reason of mandatory
provisions of law, the perfection or priority of the security interest granted
hereunder in any Power Marketing Security Agreement Collateral is governed by
the Uniform Commercial Code in effect in a jurisdiction other than the State of
New York, the term "UCC" shall mean the Uniform Commercial Code as in effect in
such other jurisdiction solely for the purposes of the provisions hereof
relating to such perfection or priority.

                  SECTION 1.2. Rules of Interpretation. Except as otherwise
expressly provided herein, the rules of interpretation set forth in Section 1.1
to the Indenture shall apply to this Agreement.

                                   ARTICLE II
                   ASSIGNMENT AND GRANT OF SECURITY INTERESTS

                  SECTION 2.1. Assignment and Grant of Security Interest. (a) As
security for the prompt and complete payment and performance when due of all of
the Secured Obligations, the Grantor hereby grants to the Collateral Agent, for
itself and for the ratable benefit of all the Secured Parties, a continuing
security interest of first priority (the "Security Interest") in all of the
Grantor's right, title and interest in, to and under the following, in each
case, whether now owned or existing or hereafter acquired, arising or created,
and wherever located:

                  (i) all revenues from all current and future power sales
         agreements, contracts and documents entered into by the Grantor
         associated with the Issuer, the Subsidiary Guarantor and any Additional
         Guarantor, as each such agreement, contract and document may be
         amended, supplemented, modified or replaced and in effect from time to
         time (said revenues collectively, the "Assigned Revenues"), including,
         without limitation: (i) all rights of the Grantor to receive moneys due
         and to become due under or pursuant to the Assigned Revenues and (ii)
         all rights of the Grantor to receive proceeds

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         of any insurance, bond, indemnity, warranty or guaranty with respect to
         the Assigned Revenues; and

                  (ii) all Proceeds, rents, profits, income, benefits,
         substitutions and replacements of, and to any of the property of the
         Grantor described in the preceding clauses of this Section 2.1
         (including, without limitation, all causes of action, claims and
         warranties now or hereafter held by the Grantor in respect of any of
         the items listed above) and, to the extent related to any property
         described in said clauses or such proceeds, all books, correspondence,
         credit files, records, invoices and other papers, including without
         limitation all tapes, cards, computer runs and other papers and
         documents in the possession or under the control of the Grantor or any
         computer bureau or service company from time to time acting for the
         Grantor (all of the above collectively, the "Power Marketing Security
         Agreement Collateral").

                  (b) The security interest granted to the Collateral Agent
pursuant to this Agreement extends to all Power Marketing Security Agreement
Collateral of the kind which is the subject of this Agreement which the Grantor
may acquire at any time during the continuation of this Agreement, whether such
Power Marketing Security Agreement Collateral is in transit or in the Grantor's,
the Collateral Agent's, any other Secured Party's or any other Person's
constructive, actual or exclusive occupancy or possession until the release
thereof pursuant to Section 8.8.

                  (c) The assignments and security interests under this
Agreement granted to the Collateral Agent shall not relieve the Grantor from the
performance of any term, covenant, condition or agreement on the Grantor's part
to be performed or observed under or in respect of any of the Power Marketing
Security Agreement Collateral pledged by it hereunder or from any liability to
any Person under or in respect of any of such Power Marketing Security Agreement
Collateral or impose any obligation on the Collateral Agent to perform or
observe any such term, covenant, condition or agreement on the Grantor's part to
be so performed or observed or impose any liability on the Collateral Agent for
any act or omission on the part of the Grantor or for any breach of any
representation or warranty on the part of the Grantor contained in this
Agreement or any other Project Document, or in respect of the Power Marketing
Security Agreement Collateral pledged by it hereunder or made in connection
herewith or therewith. The obligations of the Grantor contained in this
paragraph shall survive the termination of this Agreement and the discharge of
the Grantor's other obligations hereunder.

                  (d) This Agreement shall create a continuing security interest
in the Power Marketing Security Agreement Collateral until the release thereof
pursuant to Section 8.8.

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                  SECTION 2.2. Security Interest Absolute. The parties hereto
shall not challenge or question in any proceeding the validity or enforceability
of this Agreement as a whole or any term or provision contained herein or the
validity of any Lien or Financing Statement in favor of the Collateral Agent.
All rights of the Collateral Agent and the other Secured Parties and all
security interests hereunder shall, to the fullest extent permitted by law, be
absolute and unconditional irrespective of:

                  (a) any invalidity, irregularity or unenforceability of any
Finance Document or any other agreement or instrument relating thereto, or any
amendment, change or modification of any of the Finance Documents;

                  (b) any impairment, modification, change, exchange, release or
subordination of or limitation on, any liability to, or stay of actions or lien
enforcement proceedings against, the Grantor, its property or its estate in
bankruptcy resulting from any bankruptcy, arrangement, readjustment,
composition, liquidation, rehabilitation or similar proceeding against or
otherwise involving or affecting the Grantor;

                  (c) any change in the time, manner or place of payment of, or
in any other term of, all or any of the Secured Obligations, or any other
amendment or waiver of or any consent to any departure from any Finance
Document;

                  (d) any change in the time, order or method of attachment or
perfection of Liens or the filing or recording of Financing Statements or other
Security Documents and irrespective of anything contained in any filing or
agreement to which the Collateral Agent or any other Secured Party may now or
hereafter be a party;

                  (e) any exchange, release or non-perfection of any other
collateral, or any release or amendment or waiver of, or consent to departure
from, any guaranty for all or any of the Secured Obligations; or

                  (f) any other circumstance which might otherwise constitute a
defense available to, or a discharge of, the Grantor or a third party pledgor,
except as otherwise provided herein.

                  SECTION 2.3. Power of Attorney. (a) The Grantor hereby
irrevocably constitutes and appoints the Collateral Agent, on behalf of itself
and the other Secured Parties, or any Person, officer or agent thereof whom the
Collateral Agent may designate, as the Grantor's true and lawful
attorney-in-fact with full irrevocable power and authority in the place and
stead of the Grantor and in the name of the Grantor or in its own name, at the
Grantor's

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cost and expense, to exercise at any time in the Collateral Agent's discretion
all or any of the following powers, which, being coupled with an interest, shall
be irrevocable until the Debt Termination Date (as defined in the Intercreditor
Agreement):

                           (i) to receive, take, endorse, sign, assign and
         deliver, all in the Collateral Agent's name or the Grantor's name, any
         and all checks, notes, drafts, and other documents or instruments
         relating to the Power Marketing Security Agreement Collateral;

                           (ii) to receive, open and dispose of all mail
         addressed to the Grantor and to notify postal authorities to change the
         address for delivery thereof to such address as the Collateral Agent
         designates;

                           (iii) to request from account debtors of the Grantor,
         in the Grantor's name or in the name of the Collateral Agent or the
         Collateral Agent's designee, information concerning the Power Marketing
         Security Agreement Collateral and the amounts owing thereon;

                           (iv) to transmit to account debtors indebted on the
         Power Marketing Security Agreement Collateral notice of the Collateral
         Agent's interest therein;

                           (v) to notify account debtors indebted on the Power
         Marketing Security Agreement Collateral to make payment directly to the
         Collateral Agent;

                           (vi) to take or bring, in the Grantor's name or in
         the Collateral Agent's name on behalf of the Secured Parties, all
         steps, actions, suits or proceedings deemed by the Collateral Agent to
         be necessary or desirable to enforce or effect collection of any
         amounts owing on the Power Marketing Security Agreement Collateral;

                           (vii) to the fullest extent permitted by law, to
         prepare, sign and file any Financing Statements or file this Agreement
         in the name of the Grantor as debtor;

                           (viii) if the Grantor shall have failed to do so in a
         timely manner, to take or cause to be taken all actions necessary to
         perform or comply, or cause performance or compliance with, the
         covenants of the Grantor contained in any Transaction Document;

                           (ix) to sign and endorse any invoices, freight or
         express bills, bills of lading, storage or warehouse receipts, drafts
         against debtors, assignments, verifications,

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         notices and other documents in connection with any of the Power
         Marketing Security Agreement Collateral;

                           (x) to defend any suit, action or proceeding brought
         against the Grantor with respect to any Power Marketing Security
         Agreement Collateral;

                           (xi) to settle, compromise or adjust any suit, action
         or proceeding described in the preceding clause (x) and, in connection
         therewith, to give such discharges or releases as the Collateral Agent,
         acting pursuant to the Intercreditor Agreement, or as otherwise
         expressly provided herein, may deem appropriate;

                           (xii) generally, to sell or transfer and make any
         agreement with respect to or otherwise deal with any of the Power
         Marketing Security Agreement Collateral as fully and completely as
         though the Secured Parties were the absolute owner thereof for all
         purposes, and to do, at the Secured Parties' option and the Grantor's
         expense, at any time, or from time to time, all acts and things which
         the Collateral Agent, acting pursuant to the Intercreditor Agreement,
         or as otherwise expressly provided herein, deem necessary to protect,
         preserve or realize upon the Power Marketing Security Agreement
         Collateral and the Liens of the Secured Parties thereon;

                           (xiii) to execute, in connection with any
         foreclosure, any endorsements, assignments or other instruments of
         conveyance or transfer with respect to the Power Marketing Security
         Agreement Collateral;

                           (xiv) to exercise the Grantor's rights under any
         power sale agreement, contract or document under which the Assigned
         Revenues arise; and

                           (xv) to exercise any and all other rights, remedies,
         powers and privileges of the Grantor with respect to the Power
         Marketing Security Agreement Collateral;

provided, however, that the Collateral Agent shall not exercise its powers under
clauses (i), (ii), (iii), (iv), (v), (vi),(ix), (x), (xi), (xii), (xiii), (xiv)
or (xv) unless a Trigger Event of which the Collateral Agent has actual
knowledge has occurred and is continuing.

                  (b) The Grantor hereby ratifies all that said attorney shall
lawfully do or cause to be done by virtue hereof. The Grantor hereby
acknowledges and agrees that in acting pursuant to this power-of-attorney the
Collateral Agent shall be acting in its own interest and in the interest of the
other Secured Parties and the Grantor acknowledges and agrees that the
Collateral Agent and the other Secured Parties shall have no fiduciary duties to
the Grantor and

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the Grantor hereby waives any claims to the rights of a beneficiary of a
fiduciary relationship hereunder.

                  SECTION 2.4. Inspection and Verification. The Collateral Agent
and such Persons as the Collateral Agent may reasonably designate shall have the
right, no more often than once each year, unless an Event of Default has
occurred and is continuing, and, if an Event of Default has occurred and is
continuing, at any reasonable time or times, in each case upon ten (10) days'
notice and at the Grantor's own cost and expense, to inspect the Power Marketing
Security Agreement Collateral, all records related thereto (and to make extracts
and copies from such records) and the premises upon which any of the Power
Marketing Security Agreement Collateral is located, to discuss the Grantor's
affairs with the appropriate officers of the Grantor and its independent
accountants and to verify under reasonable procedures the validity, amount,
quality, quantity, value, condition and status of, or any other matter relating
to, the Power Marketing Security Agreement Collateral, including, in the case of
Power Marketing Security Agreement Collateral in the possession of any third
party, by contacting account debtors or the third party possessing such Power
Marketing Security Agreement Collateral for the purpose of making such a
verification. The Collateral Agent shall have the absolute right to share any
information it gains from such inspection or verification with any other Secured
Party.

                                   ARTICLE III
                GENERAL REPRESENTATIONS, WARRANTIES AND COVENANTS

                  The Grantor hereby represents, warrants and covenants to the
Collateral Agent and the other Secured Parties, which representations,
warranties and covenants shall survive execution and delivery of this Agreement
and the making and repayment of the Secured Obligations, subject to the
provisions of Section 8.9, as follows:

                  SECTION 3.1. Title and Authority. The Grantor has good and
valid rights in and title to the Power Marketing Security Agreement Collateral
with respect to which it has purported to grant a Security Interest hereunder
and has full power and authority to grant to the Collateral Agent the Security
Interest in such Power Marketing Security Agreement Collateral pursuant hereto
and to execute, deliver and perform its obligations in accordance with the terms
of this Agreement, without the consent or approval of any Person other than any
consent or approval that has been obtained and is in full force and effect.

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                  SECTION 3.2.  Validity, Perfection and Priority of Lien.

                  (a) This Agreement creates in favor of the Collateral Agent,
for itself and for the ratable benefit of the Secured Parties, a legal, valid
and enforceable security interest in the Power Marketing Security Agreement
Collateral and the proceeds thereof owned by the Grantor, and when Financing
Statements in appropriate form are filed in the offices specified on Schedule I
hereto, the Lien created under this Agreement will constitute a fully perfected
Lien on, and security interest in, all right, title and interest of the Grantor
in such Power Marketing Security Agreement Collateral and the proceeds thereof,
in each case prior and superior in right to any other Person, subject only to
Permitted Liens.

                  (b) (i) Fully executed Financing Statements or other
appropriate filings, recordings or registrations containing a description of the
Power Marketing Security Agreement Collateral have been delivered to the
Collateral Agent for filing in each governmental, municipal or other office
specified in Schedule I, which are all the filings, recordings and registrations
that are necessary to publish notice of and protect the validity of and to
establish a valid and perfected security interest in favor of the Collateral
Agent (for the benefit of itself and for the ratable benefit of the Secured
Parties) in respect of all Power Marketing Security Agreement Collateral in
which the Security Interest may be perfected by filing, recording or
registration in the United States (or any political subdivision thereof) and its
territories and possessions, and no further or subsequent filing, refiling,
recording, rerecording, registration or reregistration is necessary in any such
jurisdiction, except as provided under Applicable Law with respect to the filing
of continuation statements. The Grantor will pay any applicable filing fees and
related expenses. The Grantor hereby irrevocably authorizes the Collateral Agent
to file any such Financing Statements without its signature as the debtor.

                  SECTION 3.3. No Liens; Other Financing Statements. (a) Except
for the Lien granted to the Collateral Agent for itself and the ratable benefit
of the Secured Parties hereunder and Permitted Liens, the Grantor is, and as to
all Power Marketing Security Agreement Collateral whether now existing or
hereafter acquired after the date hereof, the Grantor will and will continue to
be the owner of valid and marketable title in and to each item of the Power
Marketing Security Agreement Collateral free and clear of any and all Liens
other than Permitted Liens and the Grantor shall defend the Power Marketing
Security Agreement Collateral against all claims and demands of all Persons at
any time claiming the same or any interest therein adverse to the Collateral
Agent or any other Secured Party.

                  (b) Other than Financing Statements filed in connection
herewith, there is no Financing Statement (or similar statement or instrument of
registration under the law of any jurisdiction) covering or purporting to cover
any interest of any kind in the Power Marketing

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Security Agreement Collateral except (i) Financing Statements filed in
connection with Permitted Liens, and (ii) Financing Statements for which proper
termination statements have been delivered to the Collateral Agent for filing.
The Grantor will not execute or authorize any Financing Statement (or similar
statement or instrument of registration under the law of any jurisdiction) or
statements relating to the Power Marketing Security Agreement Collateral to be
filed in any public office, except Financing Statements filed or to be filed in
respect of and covering the security interests granted hereby to the Collateral
Agent by the Grantor and Financing Statements filed in respect of and covering
Permitted Liens.

                  SECTION 3.4. Chief Executive Office; Name; Records. (a) The
chief executive office and principal place of business of the Grantor is located
at 1221 Nicollet Mall, Suite 700, Minneapolis, Minnesota 55403. Except as
permitted by the Indenture, the Grantor will not (i) move its chief executive
office, or (ii) change its name from, nor carry on business under any name other
than "NRG Power Marketing, Inc.," unless it has complied with the requirements
of Section 3.4(b). The originals of all documents evidencing all Assigned
Revenues of the Grantor, and the only original books of account and records
concerning the Power Marketing Security Agreement Collateral are, and will
continue to be, kept at, and controlled and directed (including, without
limitation, for general accounting purposes) from, such chief executive office,
or at such new location for such chief executive office as the Grantor may
establish in accordance with Section 3.4(b).

                  (b) The Grantor shall not establish a new location for its
 chief executive office or change its name or the name under which it presently
 conducts its business unless (i) it has given to the Collateral Agent not less
 than thirty (30) days' prior written notice of its intention so to do, clearly
 describing such new location or specifying such new name, as the case may be,
 and providing such other information in connection therewith as the Collateral
 Agent may reasonably request, and (ii) with respect to such new location or
 such new name, as the case may be, the Grantor shall have taken all action,
 satisfactory to the Collateral Agent, to maintain the security interest of the
 Collateral Agent in the Power Marketing Security Agreement Collateral intended
 to be granted hereby at all times fully perfected and in full force and effect.

                  SECTION 3.5. Additional Statements and Schedules. The Grantor
shall execute and deliver to the Collateral Agent, from time to time, for its
convenience in maintaining a record of the Power Marketing Security Agreement
Collateral, such written statements and schedules as the Collateral Agent may
reasonably require, designating, identifying or describing the Power Marketing
Security Agreement Collateral.

                  SECTION 3.6. Further Actions. The Grantor will, at its own
expense, make, execute, endorse, acknowledge, file and/or deliver to the
Collateral Agent from time to time

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such lists, descriptions and designations of its Power Marketing Security
Agreement Collateral, warehouse receipts, receipts in the nature of warehouse
receipts, bills of lading, documents of title, vouchers, invoices, schedules,
confirmatory assignments, conveyances, Financing Statements, transfer
endorsements, powers of attorney, certificates, reports and other assurances or
instruments and take such further steps relating to the Power Marketing Security
Agreement Collateral and other property or rights covered by the Security
Interest hereby granted by the Grantor to perfect, preserve or protect its
security interest in the Power Marketing Security Agreement Collateral within
thirty (30) days after any request by the Collateral Agent or such earlier date
as may be required by applicable law or necessary to preserve or protect the
security interests in the Power Marketing Security Agreement Collateral granted
by the Grantor pursuant to this Agreement, including the payment of any fees and
taxes required in connection with the execution and delivery of this Agreement,
the granting of the Lien created hereby and the filing of any Financing
Statements or other documents in connection herewith.

                                   ARTICLE IV
                           CASH PROCEEDS OF COLLATERAL

                  Upon the occurrence and during the continuance of an Event of
Default, the Grantor shall deposit the cash proceeds of any of the Power
Marketing Security Agreement Collateral required to be delivered to the
Collateral Agent pursuant hereto into the Revenue Account. In addition to the
foregoing, the Grantor agrees that, at any time after the occurrence and during
the continuance of an Event of Default, if the proceeds of any Power Marketing
Security Agreement Collateral hereunder shall be received by it, the Grantor
shall, upon the request of the Collateral Agent, as promptly as possible deposit
such proceeds into the Revenue Account. Until so deposited, all such proceeds
shall be held in trust by the Grantor for and as the property of the Collateral
Agent and shall not be commingled with any other funds or property of the
Grantor.

                                    ARTICLE V
                          SPECIAL PROVISIONS CONCERNING
                                ASSIGNED REVENUES

                  SECTION 5.1. Additional Representations and Warranties. As of
the time when each of its Assigned Revenues arises, the Grantor shall be deemed
to have represented and warranted to the best of its knowledge that such
Assigned Revenue and all records, papers and documents relating thereto (if any)
are genuine and in all respects what they purport to be, and that all papers and
documents (if any) relating thereto (i) will (subject to dispute, return,
replacement, settlement or compromise) represent the genuine, legal, valid and
binding

                                       11
<PAGE>   16
obligation of the account debtor evidencing indebtedness unpaid and owed by such
account debtor arising out of the performance of labor or services or the sale
and delivery of the merchandise listed therein, or both, (ii) will be the only
original writings evidencing and embodying such obligation of the account debtor
named therein (other than copies created for purposes other than general
accounting purposes), (iii) will (subject to dispute, return, replacement,
settlement or compromise) evidence true and valid obligations, enforceable in
accordance with their respective terms, not subject to the fulfillment of any
contract or condition whatsoever unless set forth in the writing and not subject
to any defenses, set-offs or counterclaims or stamp or other taxes, and not
subject to any provisions prohibiting the Security Interest granted hereunder,
and (iv) will be in compliance and will conform with all Applicable Law.

                  SECTION 5.2. Maintenance of Records; Legending of Records. The
Grantor will keep and maintain at its own cost and expense satisfactory and
complete records of its Assigned Revenues for at least five (5) years from the
date on which the Assigned Revenue comes into existence, including, without
limitation, records of all payments received and all credits granted thereon,
and the Grantor will make the same available to the Collateral Agent and the
other Secured Parties for inspection in accordance with Section 2.4. The Grantor
shall, at its own cost and expense, deliver all tangible evidence of its
Assigned Revenues (including, without limitation, all documents evidencing the
Assigned Revenues) and books and records that the Collateral Agent may request
to the Collateral Agent or to its representatives (copies of which evidence and
books and records may be retained by the Grantor) at any reasonable time during
normal business hours upon the Collateral Agent's demand. The Grantor shall, at
the Collateral Agent's request and at the Grantor's own cost and expense, legend
in form and substance satisfactory to the Collateral Agent, the Power Marketing
Security Agreement Collateral, as well as books, records and documents of the
Grantor evidencing or pertaining to the Power Marketing Security Agreement
Collateral, with an appropriate reference to the fact that the items
constituting the Power Marketing Security Agreement Collateral have been
assigned to the Collateral Agent and that the Collateral Agent has a security
interest therein.

                  SECTION 5.3. Modification of Terms; No Payment to Grantor. The
Grantor shall not, other than in the ordinary course of business, rescind or
cancel any indebtedness evidenced by any Assigned Revenue or make any adjustment
with respect thereto, or extend or renew the same, or compromise or settle any
dispute, claim, suit or legal proceeding relating thereto, or sell any Assigned
Revenue or interest therein, without the prior written consent of the Collateral
Agent, acting pursuant to the Intercreditor Agreement, or as otherwise expressly
provided herein. The Grantor will duly fulfill all obligations on its part to be
fulfilled under or in connection with the Assigned Revenues and will do nothing
to impair the rights of the Collateral Agent in the Assigned Revenues.

                                       12
<PAGE>   17
                  SECTION 5.4. Collection. The Grantor shall take all
commercially reasonable actions to cause to be collected from the account
debtors of each of the Assigned Revenues, as and when due (including Assigned
Revenues that are delinquent, such Assigned Revenues to be collected in
accordance with generally accepted commercial collection procedures), any and
all amounts owing under or on account of such Assigned Revenues, and apply
forthwith upon receipt thereof all such amounts as are so collected to the
outstanding balance of such Assigned Revenues.

                  SECTION 5.5. Instruments. If any of the Assigned Revenues
becomes evidenced by an Instrument having a face value in excess of $5,000 and a
maturity of thirty (30) days or longer, the Grantor shall promptly notify the
Collateral Agent thereof in writing, and within ten (10) days of a request by
the Collateral Agent therefor, shall deliver such Instrument to the Collateral
Agent appropriately endorsed to the order of the Collateral Agent as further
security hereunder. Notwithstanding the foregoing, at such time that an Event of
Default shall have occurred and be continuing, or at such time as the Grantor
shall own or acquire Instruments which in the aggregate exceed $20,000, the
Grantor shall deliver all Instruments to the Collateral Agent within ten (10)
days, appropriately endorsed to the order of the Collateral Agent as further
security hereunder.

                                   ARTICLE VI
                        DUTY OF CARE OF COLLATERAL AGENT

                  SECTION 6.1. Collateral Agent's Duties; Reasonable Care. The
Collateral Agent shall have the duty to exercise reasonable care in the custody
and preservation of any Power Marketing Security Agreement Collateral in its
possession, which duty shall be fully satisfied if the Collateral Agent
maintains safe custody of such Power Marketing Security Agreement Collateral in
accordance with customary banking standards.

                  SECTION 6.2. Further Protection. In acting hereunder, the
Collateral Agent shall be entitled to the same rights, indemnities and
immunities as afforded to it under the Intercreditor Agreement.

                                   ARTICLE VII
                   REMEDIES UPON OCCURRENCE OF A TRIGGER EVENT

                  SECTION 7.1. Remedies; Obtaining the Power Marketing Security
Agreement Collateral upon Trigger Event. (a) Upon the occurrence and during the
continuance of a Trigger Event, the Collateral Agent, acting pursuant to the
Intercreditor Agreement, or as

                                       13
<PAGE>   18
otherwise expressly provided herein, shall be entitled to exercise on behalf of
itself and the other Secured Parties, all the rights and remedies of a secured
party under the UCC as in effect in any relevant jurisdiction and all rights now
or hereafter existing under all other Applicable Law to enforce this Agreement
and the security interests contained herein, and, in addition, subject to any
Applicable Laws then in effect, the Collateral Agent, acting pursuant to the
Intercreditor Agreement, or as otherwise expressly provided herein, may, but is
under no obligation to, in addition to its other rights and remedies hereunder,
including without limitation under Section 7.2 and Section 7.6, and also the
rights of the Collateral Agent and the other Secured Parties under any of the
Transaction Documents, do any of the following to the fullest extent permitted
by applicable law:

                  (i) personally, or by agents, trustees or attorneys,
immediately take possession of the Power Marketing Security Agreement Collateral
or any part thereof, from the Grantor or any other Person who then has
possession of any part thereof with or without notice or process of law, and for
that purpose may enter upon the Grantor's premises or such other Person's
premises where any of the Power Marketing Security Agreement Collateral is
located and remove the same and use in connection with such removal any and all
services, supplies, aids and other facilities of the Grantor;

                  (ii) instruct the obligor or obligors of any agreement,
instrument or other obligation (including, without limitation, the Assigned
Revenues) constituting the Power Marketing Security Agreement Collateral to make
any payment required by the terms of such instrument or agreement directly to
the Collateral Agent; and

                  (iii) take possession of the Power Marketing Security
Agreement Collateral or any part thereof, by directing the Grantor in writing to
turn over the same to the Collateral Agent at its chief executive office or, to
the extent such Power Marketing Security Agreement Collateral may be moved, to
deliver the same to the Collateral Agent at any other place or places designated
by the Collateral Agent, in which event the Grantor shall, at its own expense
(A) forthwith turn over the same to the Collateral Agent at one of the places
designated by the Collateral Agent, (B) store and keep any Power Marketing
Security Agreement Collateral so turned over or delivered to the Collateral
Agent at such place or places pending further action by the Collateral Agent as
provided in Section 7.2 and (C) while the Power Marketing Security Agreement
Collateral shall be so stored and kept, provide such guards and maintenance
services as shall be necessary to protect the same and to preserve and maintain
the Power Marketing Security Agreement Collateral in good condition.

                  (b) The Grantor's obligation to turn over or deliver the Power
Marketing Security Agreement Collateral as set forth above is of the essence of
this Agreement and,

                                       14
<PAGE>   19
accordingly, upon application to a court of equity having jurisdiction, the
Collateral Agent shall be entitled to obtain a decree requiring specific
performance by the Grantor of said obligation.

                  (c) When Power Marketing Security Agreement Collateral is in
the Collateral Agent's possession, the Grantor shall pay (or reimburse the
Collateral Agent on demand for) all reasonable expenses (including the cost of
any insurance and payment of taxes or other charges) incurred in the custody,
preservation, use or operation of the Power Marketing Security Agreement
Collateral, and the obligation to reimburse all such expenses shall be secured
hereby.

                  SECTION 7.2. Remedies; Disposition of the Power Marketing
Security Agreement Collateral. Any Power Marketing Security Agreement Collateral
repossessed by the Collateral Agent under or pursuant to Section 7.1 and any
other Power Marketing Security Agreement Collateral, whether or not so
repossessed by the Collateral Agent, may, to the extent permitted by any
contract terms governing such Power Marketing Security Agreement Collateral and
to the fullest extent permitted by applicable law, be sold, leased or otherwise
disposed of under one or more contracts or as an entirety, whether by public or
private sale and without the necessity of gathering at the place of sale the
property to be sold, and in general in such manner, at such time or times, at
such place or places and on such terms (whether cash or credit, and in the case
of credit, without assumption of future credit risk) as the Collateral Agent
may, in compliance with Applicable Law, determine to be commercially reasonable.
If any Power Marketing Security Agreement Collateral is sold by the Collateral
Agent upon credit or for future delivery, the Collateral Agent shall not be
liable for the failure of the purchaser to pay for the same and in such event
the Collateral Agent may resell the Power Marketing Security Agreement
Collateral. In no event shall the Grantor be credited with any part of the
proceeds of sale of any Power Marketing Security Agreement Collateral until
payment thereof in cash or cash equivalents has actually been received by the
Collateral Agent. Any of the Power Marketing Security Agreement Collateral may
be sold, leased or otherwise disposed of, or options or contracts may be entered
to do so, in the condition in which the same existed when taken by the
Collateral Agent or after any overhaul or repair which the Collateral Agent
shall determine to be commercially reasonable. Any such disposition shall be
made upon not less than ten (10) days' written notice to the Grantor specifying
the time such disposition is to be made and, if such disposition shall be a
public sale, specifying the place of such sale. Any such sale may be adjourned
by announcement at the time and place fixed therefor, and such sale may, without
further notice, be made at the time and place to which it was so adjourned. To
the extent permitted by Applicable Law, the Collateral Agent or any other
Secured Party may itself bid for and become the buyer of the Power Marketing
Security

                                       15
<PAGE>   20
Agreement Collateral or any item thereof offered for sale at a public auction
without accountability to the Grantor.

                  SECTION 7.3. Waiver. (a) EXCEPT AS OTHERWISE PROVIDED IN THIS
AGREEMENT, THE GRANTOR HEREBY WAIVES, TO THE EXTENT PERMITTED BY APPLICABLE LAW,
NOTICE OR JUDICIAL HEARING IN CONNECTION WITH THE COLLATERAL AGENT'S TAKING
POSSESSION OR THE COLLATERAL AGENT'S DISPOSITION OF ANY OF THE COLLATERAL IN
ACCORDANCE WITH THIS AGREEMENT, INCLUDING, WITHOUT LIMITATION, ANY AND ALL PRIOR
NOTICE AND HEARING FOR ANY PREJUDGMENT REMEDY OR REMEDIES AND ANY SUCH RIGHT
WHICH THE GRANTOR WOULD OTHERWISE HAVE UNDER THE CONSTITUTION OR ANY STATUTE OF
THE UNITED STATES OR OF ANY STATE, AND THE GRANTOR HEREBY FURTHER WAIVES:

                           (i) all damages occasioned by such taking of
         possession except any damages which are finally judicially determined
         to have been the direct result of the Collateral Agent's gross
         negligence or wilful misconduct;

                           (ii) all other requirements as to the time, place and
         terms of sale or other requirements with respect to the enforcement of
         the Collateral Agent's and the other Secured Parties' rights hereunder;

                           (iii) demand of performance or other demand, notice
         of intent to demand or accelerate, notice of acceleration, presentment,
         protest, advertisement or notice of any kind to or upon the Grantor or
         any other Person; and

                           (iv) all rights of redemption, appraisement,
         valuation, stay, extension or moratorium now or hereafter in force
         under any applicable law in order to prevent or delay the enforcement
         of this Agreement or the absolute sale of the Power Marketing Security
         Agreement Collateral or any portion thereof, and the Grantor, for
         itself and all who may claim under it, insofar as it or they may now or
         hereafter lawfully do so, hereby waives the benefit of such laws.

                  (b) Without limiting the generality of the foregoing, the
Grantor hereby: (i) authorizes the Collateral Agent, in its sole discretion and
without notice to or demand upon the Grantor and without otherwise affecting the
obligations of the Grantor hereunder from time to time, to take and hold other
collateral granted to it by any other Person (in addition to the Power Marketing
Security Agreement Collateral) for payment of any Secured Obligations, or any
part thereof, and to exchange, enforce or release such other collateral or any
part thereof,

                                       16
<PAGE>   21
and to accept and hold any endorsement or guarantee of payment of the Secured
Obligations or any part thereof, and to release or substitute any endorser or
guarantor or any other Person granting security for or in any way obligated upon
any Secured Obligations, or any part thereof; and (ii) waives and releases any
and all right to require the Collateral Agent or the other Secured Parties to
collect any of the Secured Obligations from any specific item or items of Power
Marketing Security Agreement Collateral or from any other party liable as
guarantor or in any other manner in respect of any of the Secured Obligations or
from any collateral (other than the Power Marketing Security Agreement
Collateral) for any of the Secured Obligations.

                  (c) Any sale of, or the grant of options to purchase, or any
other realization upon, any Power Marketing Security Agreement Collateral shall,
provided that it is done in accordance with applicable law and this Agreement,
operate to divest all right, title, interest, claim and demand, either at law or
in equity, of the Grantor therein and thereto, and shall be a perpetual bar both
at law and in equity against the Grantor and against any and all Persons
claiming or attempting to claim the Power Marketing Security Agreement
Collateral so sold, optioned or realized upon, or any part thereof, from,
through and under the Grantor.

                  SECTION 7.4. Application of Proceeds; Grantor Liable for
Deficiency. The Collateral Agent shall apply the net proceeds of any collection,
sale or other realization of all or any part of the Power Marketing Security
Agreement Collateral pursuant to this Agreement, and any other cash at the time
of such collection, sale or other realization held by the Collateral Agent under
this Agreement, in accordance with Article V of the Intercreditor Agreement.

                  SECTION 7.5. No Waiver; Remedies Cumulative. No failure or
delay on the part of any Secured Party in exercising any right, remedy, power or
privilege hereunder and no course of dealing between the Grantor and any Secured
Party shall operate as a waiver thereof; nor shall any single or partial
exercise of any right, power or privilege hereunder preclude any other or
further exercise thereof or the exercise of any other right, remedy, power or
privilege. A waiver by any Secured Party of any right or remedy hereunder on any
one occasion shall not be construed as a bar to any right or remedy which any
Secured Party would otherwise have on any future occasion. The rights and
remedies herein expressly provided are cumulative and may be exercised singly or
concurrently and as often and in such order as any Secured Party deems expedient
and are not exclusive of any rights or remedies which the Secured Parties would
otherwise have whether by agreement or now or hereafter existing under
Applicable Law. No notice to or demand on the Grantor in any case shall entitle
the Grantor to any other or further notice or demand in similar or other
circumstances or constitute a waiver of the rights of the Secured Parties to any
other or future action in any circumstances without notice or demand.

                                       17
<PAGE>   22
                  SECTION 7.6. Discontinuance of Proceedings. In case any
Secured Party shall have instituted any proceeding to enforce any right, power
or remedy under this Agreement by foreclosure, sale, entry or otherwise, and
such proceeding shall have been discontinued or abandoned for any reason or
shall have been determined adversely to such Secured Party, then, in every such
case, subject to the terms of any final non-appealable judgment rendered in any
such proceeding, the Grantor, the Secured Parties and each holder of any of the
Secured Obligations shall be restored to their former positions and rights
hereunder with respect to the Power Marketing Security Agreement Collateral,
subject to the Security Interest created under this Agreement, and all rights,
remedies and powers of the Secured Parties shall continue as if no such
proceeding had been instituted.

                                  ARTICLE VIII
                                 MISCELLANEOUS

                  SECTION 8.1. Notices. Unless otherwise specifically herein
provided, all notices required or permitted under the terms and provisions
hereof shall be in writing and any such notice shall become effective if given
in accordance with the provisions of Section 12.5 of the Indenture.

                  SECTION 8.2. Amendment. No waiver, amendment, modification or
termination of any provision of this Agreement, or consent to any departure by
the Grantor therefrom, shall in any event be effective without the prior written
consent of the Collateral Agent, acting pursuant to the Intercreditor Agreement,
or as otherwise expressly provided herein, and none of the Power Marketing
Security Agreement Collateral shall be released without the written consent of
the Collateral Agent, acting pursuant to the Intercreditor Agreement, or as
otherwise expressly provided herein. Any such waiver or consent shall be
effective only in the specific instance and for the specific purpose for which
given.

                  SECTION 8.3. Successors and Assigns. This Agreement shall be
binding upon and inure to the benefit of the Grantor and the Secured Parties,
all future holders of the Secured Obligations and their respective successors,
transferees and assigns (to the extent such successors, transferees and assigns
are permitted under the Finance Documents and the documents regarding additional
Permitted Indebtedness), except that the Grantor may not assign or transfer any
of its rights or obligations under this Agreement without the prior written
consent of the Collateral Agent and in accordance with this Agreement.

                  SECTION 8.4. Survival. All agreements, statements,
representations and warranties made by the Grantor herein or in any certificate
or other instrument delivered by the Grantor or on its behalf under this
Agreement shall be considered to have been relied upon by

                                       18
<PAGE>   23
the Secured Parties and shall survive the execution and delivery of this
Agreement and the other Finance Documents regardless of any investigation made
by any Secured Party or made on their behalf.

                  SECTION 8.5. Headings Descriptive. The headings of the several
sections of this Agreement are inserted for convenience only and shall not in
any way affect the meaning or construction of any provision of this Agreement.

                  SECTION 8.6. Severability. In case any provision in or
obligation under this Agreement shall be invalid, illegal or unenforceable in
any jurisdiction, the validity, legality and enforceability of the remaining
provisions or obligations, or of such provision or obligation in any other
jurisdiction, shall not in any way be affected or impaired thereby.

                  SECTION 8.7. Grantor's Duties. Anything herein contained to
the contrary notwithstanding, the Grantor shall remain liable to perform all of
its obligations under or with respect to the Power Marketing Security Agreement
Collateral, and the Secured Parties shall not have any obligations or
liabilities under or with respect to any Power Marketing Security Agreement
Collateral by reason of or arising out of this Agreement, nor shall the Secured
Parties be required or obligated in any manner to perform or fulfill any of the
obligations of the Grantor under or with respect to any Power Marketing Security
Agreement Collateral.

                  SECTION 8.8. Termination; Release. (a) Upon the occurrence of
the Debt Termination Date, this Agreement shall terminate (except as provided in
Section 8.4), and the Collateral Agent, at the written request and expense of
the Grantor, will promptly execute and deliver to the Grantor the proper
instruments (including UCC termination statements on form UCC-3) acknowledging
the termination of this Agreement, and will duly assign, transfer and deliver to
the Grantor (without recourse and without any representation or warranty of any
kind) such of the Power Marketing Security Agreement Collateral as may be in the
possession of the Collateral Agent and has not theretofore been disposed of or
otherwise applied or released.

                  (b) Upon the sale or disposition of any portion of the Power
Marketing Security Agreement Collateral permitted pursuant to the terms of the
Finance Documents, including, but not limited to, any Permitted Asset Sale, the
purchaser of such portion of the Power Marketing Security Agreement Collateral
shall, upon such purchase, acquire good title to the Power Marketing Security
Agreement Collateral so purchased, free of the security interest created by this
Agreement. The Collateral Agent, upon the request, and at the expense, of the
Grantor, shall execute and deliver all such documentation necessary to release
the security interest created in such Power Marketing Security Agreement
Collateral pursuant to this Agreement.

                                       19
<PAGE>   24
                  SECTION 8.9. Reinstatement. This Agreement shall continue to
be effective or be reinstated, as the case may be, if at any time any amount
received by any Secured Party in respect of the Secured Obligations is rescinded
or must otherwise be restored or returned by such Secured Party upon the
insolvency, bankruptcy, dissolution, liquidation or reorganization of the
Grantor or upon the appointment of any intervenor or conservator of, or trustee
or similar official for, the Grantor or any substantial part of its assets, or
upon the entry of an order by a bankruptcy court avoiding payment of such
amount, or otherwise, all as though such payments had not been made.

                  SECTION 8.10. Counterparts. This Agreement may be executed in
any number of counterparts, each of which, taken together, shall constitute one
and the same instrument and any of the parties hereto may execute this Agreement
by signing any such counterpart.

                  SECTION 8.11 Governing Law; Submission to Jurisdiction; Waiver
of Jury Trial. (a) THIS AGREEMENT IS A CONTRACT MADE UNDER THE LAWS OF THE STATE
OF NEW YORK OF THE UNITED STATES AND SHALL FOR ALL PURPOSES BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF SUCH STATE WITHOUT REGARD TO THE
CONFLICT OF LAW RULES THEREOF (OTHER THAN SECTION 5-1401 OF THE NEW YORK GENERAL
OBLIGATIONS LAW).

                  (b) Any legal action or proceeding against the Grantor with
respect to this Agreement may be brought in the courts of the State of New York
in the County of New York or of the United States for the Southern District of
New York and, by execution and delivery of this Agreement, the Grantor hereby
irrevocably submits and accepts for itself and in respect of its property,
generally and unconditionally, the jurisdiction of the aforesaid courts. The
Grantor agrees that a judgment, after exhaustion of all available appeals, in
any such action or proceeding shall be conclusive and binding upon the Grantor,
and may be enforced in any other jurisdiction, by a suit upon such judgment, a
certified copy of which shall be conclusive evidence of the judgment. The
Grantor hereby irrevocably designates, appoints and empowers CT Corporation
System with offices on the date hereof at 111 Eighth Avenue, New York, N.Y.
10011, as its designee, appointee and agent to receive, accept and acknowledge
for and on its behalf, and in respect of its property, service of any and all
legal process, summons, notice and documents which may be served in any such
action or proceeding. If for any reason such designee, appointee and agent shall
cease to be available to act as such agent, the Grantor agrees to designate a
new designee, appointee and agent in New York City on the terms and for the
purposes of this provision satisfactory to the Collateral Agent. The Grantor
further irrevocably consents to the service of process out of any of the
aforementioned courts in any such action or proceeding by the mailing of copies
thereof by registered or certified mail,

                                       20
<PAGE>   25
postage prepaid, to the Grantor at its address referred to in Section 12.5(a) of
the Indenture, such service to become effective thirty (30) days after such
mailing. Nothing herein shall affect the right of the Collateral Agent or any
other Person to serve process in any other manner permitted by law or to
commence legal proceedings or otherwise proceed against the Grantor in any other
jurisdiction.

                  (c) The Grantor hereby irrevocably waives any objection which
it may now or hereafter have to the laying of venue of any of the aforesaid
actions or proceedings arising out of or in connection with this Agreement in
the courts referred to in clause (b) above and hereby further irrevocably waives
and agrees not to plead or claim in any such court that any such action or
proceeding brought in any such court has been brought in an inconvenient forum.

                  (d) WITH REGARD TO THIS AGREEMENT, EACH PARTY HERETO HEREBY
WAIVES THE RIGHT TO A TRIAL BY JURY.

                  SECTION 8.12. Authority of Collateral Agent. The Grantor
acknowledges that the rights and responsibilities of the Collateral Agent under
this Agreement with respect to any action taken by the Collateral Agent or the
exercise or non-exercise by the Collateral Agent of any option, right, request,
judgment or other right or remedy provided for herein or resulting or arising
out of this Agreement shall, as between the Collateral Agent and the other
Secured Parties, be governed by this Agreement, the other Finance Documents and
by such other agreements with respect thereto as may exist from time to time
among them, but, as between the Collateral Agent and the Grantor, the Collateral
Agent shall be conclusively presumed to be acting as agent for the Secured
Parties with full and valid authority so to act or refrain from acting, and the
Grantor shall not be under any obligation, or entitlement, to make any inquiry
respecting such authority.

                  SECTION 8.13. Conflict with Intercreditor Agreement. In case
of a conflict between any provision of this Agreement and any provision of the
Intercreditor Agreement, the provisions of the Intercreditor Agreement shall
control. No such conflict shall be deemed to exist merely because this Agreement
imposes greater obligations on the Grantor than the Intercreditor Agreement.

                  SECTION 8.14. Indemnities and Expenses. The obligation of the
Grantor to pay the costs and expenses of, and to indemnify, defend and hold
harmless, the Collateral Agent, its agents, officers, directors and
representatives and the other Secured Parties under and in connection with this
Agreement shall be as provided in Section 2.4 of the Intercreditor Agreement as
in effect as of the date hereof. No amendment to such Section 2.4 or termination
of the Intercreditor Agreement shall affect the provisions of this Section 9.16
unless such

                                       21
<PAGE>   26
amendment or termination shall have been consented to by the parties to this
Agreement in accordance with the provisions hereof and of the other Finance
Documents.

                  SECTION 8.15. Entire Agreement. This Agreement, together with
any other agreement executed in connection herewith, is intended by the parties
as a final expression of their agreement as to the matters covered hereby and is
intended as a complete and exclusive statement of the terms and conditions
thereof.

                  SECTION 8.16. Independent Security. The security provided for
in this Agreement shall be in addition to and shall be independent of every
other security which the Collateral Agent or the other Secured Parties may at
any time hold for any of the Secured Obligations hereby secured, whether or not
under the Security Documents. The execution of any other Security Document shall
not modify or supersede the security interest or any rights or obligations
contained in this Agreement and shall not in any way affect, impair or
invalidate the effectiveness and validity of this Agreement or any term or
condition hereof. The Grantor hereby waives its right to plead or claim in any
court that the execution of any other Security Document is a cause for
extinguishing, invalidating, impairing or modifying the effectiveness and
validity of this Agreement or any term or condition contained herein. The
Collateral Agent shall be at liberty to accept further security from the Grantor
or from any third party and/or release such security without notifying the
Grantor and without affecting in any way the obligations of the Grantor under
the Security Documents or the other Finance Documents. The Collateral Agent,
acting pursuant to the Intercreditor Agreement, or as otherwise expressly
provided herein, shall determine if any security conferred upon the Collateral
Agent and the other Secured Parties under the Security Documents shall be
enforced by the Collateral Agent, as well as the sequence of securities to be so
enforced.

                  SECTION 8.17. Third Party Beneficiaries. The agreements of the
parties hereto are intended to benefit the Secured Parties and their respective
successors and assigns.

                  SECTION 8.18. Limitation of Liability. The provisions of
Section 12.11 of the Indenture shall apply to this Agreement.

                  SECTION 8.19. Merger of Collateral Agent. Any corporation into
which the Collateral Agent may be merged or converted or with which it may be
consolidated, or any corporation resulting from any merger, conversion or
consolidation to which the Collateral Agent shall be a party, or any corporation
succeeding to the business of the Collateral Agent shall be the successor of the
Collateral Agent hereunder without the execution or filing of any paper with any
party hereto or any further act on the part of any of the parties hereto except

                                       22
<PAGE>   27
where an instrument of transfer or assignment is required by law to effect such
succession, anything herein to the contrary notwithstanding.

            [THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK]

                                       23
<PAGE>   28
IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly
executed and delivered by their duly authorized officers as of the date first
above written.

                                    NRG POWER MARKETING INC. as Grantor

                                    By: /s/ Craig A. Mataczynski
                                        Name: Craig A. Mataczynski
                                        Title: President

                                    THE CHASE MANHATTAN BANK, as Collateral
                                    Agent

                                    By: /s/ Annette M. Marsula
                                        Name: Annette M. Marsula
                                        Title: Vice President
<PAGE>   29
                                                        Schedule I to Assignment
                                                          and Security Agreement

                                 Filing Offices

           Office of the Secretary of State of the State of Minnesota

                                   Sch. I - 1<PAGE>   1
                                                                    Exhibit 4.15

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

                          PLEDGE AND SECURITY AGREEMENT

                           Dated as of March 30, 2000

                                       by

                        NRG SOUTH CENTRAL GENERATING LLC
                                   as Pledgor

                                       to

                            THE CHASE MANHATTAN BANK
                               as Collateral Agent

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

<PAGE>   2

                               TABLE OF CONTENTS
<TABLE>
<CAPTION>
                                                                                     Page
                                                                                     ----
<S>                                                                                    <C>
RECITALS ...............................................................................1
AGREEMENT ..............................................................................1

                                   ARTICLE 1
                     DEFINED TERMS; RULES OF INTERPRETATION

Section 1.1 Defined Terms ..............................................................2
Section 1.2 Rules of Interpretation ....................................................3

                                   ARTICLE 2
                                     PLEDGE

Section 2.1 Pledged Collateral .........................................................3
Section 2.2 Delivery of Certificates and Instruments ...................................4
Section 2.3 Pledgor's Rights ...........................................................5
Section 2.4 Secured Parties Not Liable .................................................6
Section 2.5 Attorney-in-Fact ...........................................................7
Section 2.6 Collateral Agent May Perform ...............................................7
Section 2.7 Reasonable Care ............................................................7
Section 2.8 Security Interest Absolute .................................................8
Section 2.9 Effective as a Financing Statement .........................................8

                                   ARTICLE 3
                         REPRESENTATIONS AND WARRANTIES

Section 3.1 Necessary Filings ..........................................................9
Section 3.2 No Liens ...................................................................9
Section 3.3 Other Financing Statements .................................................9
Section 3.4 Chief Executive Office .....................................................9
Section 3.5 Consents, etc. .............................................................9
</TABLE>

                                       i
<PAGE>   3

                                   ARTICLE 4
                                   COVENANTS
<TABLE>

<S>                                                                                   <C>
Section 4.1 Sale of Pledged Collateral ................................................10
Section 4.2 No Other Liens ............................................................10
Section 4.3 Chief Executive Office ....................................................10
Section 4.4 Supplements; Further Assurances, etc ......................................10
Section 4.5 Amendment of Operating Agreement ..........................................10
Section 4.6 Certificates and Instruments ..............................................11
Section 4.7 Financing Statements ......................................................11
Section 4.8 Records; Statements and Schedules .........................................11
Section 4.9 Improper Distributions ....................................................12
Section 4.10 Bankruptcy ...............................................................12

                                   ARTICLE 5
                 EXERCISE OF REMEDIES UPON AN EVENT OF DEFAULT

Section 5.1 Remedies Generally ........................................................12
Section 5.2 Sale of Pledged Collateral ................................................12
Section 5.3 Purchase of Pledged Collateral ............................................14
Section 5.4 Application of Proceeds ...................................................14

                                   ARTICLE 6
                            MISCELLANEOUS PROVISIONS

Section 6.1 Notices ...................................................................14
Section 6.2 Continuing Security Interest ..............................................15
Section 6.3 Release ...................................................................15
Section 6.4 Reinstatement .............................................................15
Section 6.5 Independent Security ......................................................15
Section 6.6 Amendments ................................................................16
Section 6.7 Successors and Assigns ....................................................16
Section 6.8 Third Party Beneficiaries .................................................16
Section 6.9 Conflict with Indenture ...................................................16
Section 6.10 Survival .................................................................17
Section 6.11 No Waiver; Remedies Cumulative ...........................................17
Section 6.12 Counterparts .............................................................17
Section 6.13 Headings Descriptive .....................................................17
Section 6.14 Severability .............................................................17
Section 6.15 Governing Law; Submission to Jurisdiction; Waiver of Jury Trial ..........17
</TABLE>

                                       ii

<PAGE>   4

<TABLE>
<S>                                                                                   <C>
Section 6.16 Entire Agreement .........................................................19
Section 6.17 Independent Obligations ..................................................19
Section 6.18 Limitation of Liability ..................................................19
</TABLE>

                                      iii

<PAGE>   5

                          PLEDGE AND SECURITY AGREEMENT

              This PLEDGE AND SECURITY AGREEMENT (this "Agreement"), dated as of
March 30, 2000, is made by NRG SOUTH CENTRAL GENERATING LLC, a Delaware limited
liability company (the "Pledgor") to THE CHASE MANHATTAN BANK, as collateral
agent (together with its successors in such capacity, the "Collateral Agent")
for the benefit of the Secured Parties.

                                    RECITALS

              WHEREAS, the Subsidiary Guarantor is acquiring the Project from
Cajun in the Acquisition; and

              WHEREAS, in order to, among other things, fund the Acquisition of
the Project and to pay financing and other fees, expenses and costs associated
with the Acquisition, the Pledgor has determined to issue Bonds pursuant to the
Indenture initially in the aggregate principal amount of $800,000,000; and

              WHEREAS, the Initial Bonds will be issued pursuant to the
Indenture, of even date herewith, between the Pledgor, the Subsidiary Guarantor
and the Bond Trustee; and

              WHEREAS, the Pledgor, the Subsidiary Guarantor, the Members, the
Collateral Agent, and the Depositary Bank are entering into the other Security
Documents, pursuant to which the Collateral Agent, acting on behalf of the
Secured Parties, will obtain a continuing Lien on and perfected Security
Interest in the Collateral; and

              WHEREAS, the Pledgor, the Subsidiary Guarantor, the Bond Trustee,
the Depositary Bank, the Working Capital Agent and the Collateral Agent have
entered into the Intercreditor Agreement; and

              WHEREAS, as additional security for the Secured Obligations, the
Pledgor desires to grant to the Collateral Agent a Lien on and security interest
in, the Pledged Collateral.

<PAGE>   6

                                    AGREEMENT

       NOW THEREFORE, in consideration of the Secured Parties entering into the
Finance Documents and to induce the Secured Parties to release the proceeds of
the issuance and sale of the Initial Bonds, and for other good and valuable
consideration, the receipt and adequacy of which are hereby acknowledged, the
Pledgor hereby agrees with the Collateral Agent as follows:

                                    ARTICLE 1
                     DEFINED TERMS; RULES OF INTERPRETATION

       Section 1.1 Defined Terms. (a) Unless otherwise defined herein, terms
defined in Appendix A to the Trust Indenture, dated as of March 30, 2000, among
the Pledgor, Louisiana Generating LLC and The Chase Manhattan Bank as Bond
Trustee (the "Indenture") shall have such defined meanings when used herein.

              (b) The following terms shall have the following respective
meanings:

              "Bankruptcy Event" shall mean, for any Person:

              (a) such Person shall (i) apply for or authorize or approve or
       consent to the appointment of, or the taking of possession by, a
       receiver, custodian, trustee or liquidator of itself or all or a
       substantial part of its property, (ii) admit in writing its inability or
       be generally unable to pay its debts as such debts become due, (iii) make
       a general assignment for the benefit of its creditors, (iv) commence a
       voluntary case under the Federal Bankruptcy Code, (v) file a petition
       seeking to take advantage of any other Debtor Relief Law, (vi) fail to
       controvert in a timely and appropriate manner, or acquiesce in writing
       to, any petition filed against it in an involuntary case under the
       Federal Bankruptcy Code or any other Debtor Relief Law or (vii) take any
       action for the purpose of effecting any of the foregoing including,
       without limitation, commencing a shareholder vote in connection with any
       of the foregoing; or

              (b) a proceeding or case shall be commenced without the
       application or consent of such Person in any court of competent
       jurisdiction, seeking (i) its liquidation, reorganization, dissolution,
       winding-up or the composition or readjustment of debts or (ii) the
       appointment of a trustee, receiver, custodian,

                                        2

<PAGE>   7

       liquidator or the like of such Person or all or a substantial part of its
       property under any Debtor Relief Law and such proceeding or case shall
       continue undismissed, or any order, judgment or decree approving any of
       the foregoing shall be entered and continue unstayed and in effect, for a
       period of sixty (60) or more consecutive days, or any order for relief
       against such Person shall be entered in any involuntary case under the
       Federal Bankruptcy Code or any other Debtor Relief Law.

              "Financing Statements" shall mean all financing statements,
recordings, filings or other instruments of registration necessary and
appropriate to perfect a security interest or Lien by filing in any appropriate
filing or recording office in accordance with the UCC as enacted in any and all
relevant jurisdictions or any other relevant applicable law.

              "Membership Interests" shall have the meaning ascribed thereto in
Section 2.1(a)(i).

              "Operating Agreement" shall mean the Third Amended and Restated
Limited Liability Company Agreement of Louisiana Generating LLC, dated as of
March 22, 2000, by the Pledgor.

              "Pledged Collateral" shall have the meaning ascribed thereto in
Section 2.1(a).

              "Securities Act" shall have the meaning ascribed thereto in
Section 5.2(b).

              Section 1.2 Rules of Interpretation. Except as otherwise expressly
provided herein, the rules of interpretation set forth in Section 1.1 to the
Indenture shall apply to this Agreement.

                                    ARTICLE 2
                                     PLEDGE

       Section 2.1 Pledged Collateral. (a) As collateral security for the prompt
and complete payment and performance when due, whether at stated maturity, by
acceleration or otherwise (including the payment of amounts which would become
due but for the operation of the automatic stay under Section 362(a) of the U.S.
Bankruptcy Code, 11 U.S.C. Section 362(a)), of all of the Secured Obligations,
whether

                                        3

<PAGE>   8

now existing or hereafter arising and howsoever evidenced, the Pledgor hereby
pledges, grants, assigns, hypothecates, transfers and delivers to the Collateral
Agent, for its benefit and the ratable benefit of the other Secured Parties, a
first priority security interest in the following, whether now existing or
hereafter from time to time acquired (collectively, the "Pledged Collateral"):

                     (i) all of the Pledgor's membership interests in the
       Subsidiary Guarantor (the "Membership Interests") and all of the
       Pledgor's rights to acquire membership interests in the Subsidiary
       Guarantor in addition to or in exchange or substitution for the
       Membership Interests;

                     (ii) all of the Pledgor's rights, privileges, authority and
       powers as a member of the Subsidiary Guarantor under the Operating
       Agreement;

                     (iii) all certificates or other documents (if any)
       representing any and all of the foregoing in clauses (i) and (ii),
       including, without limitation, the certificates listed on Schedule I
       hereto;

                     (iv) all dividends, distributions, cash, securities,
       instruments and other property or proceeds of any kind to which the
       Pledgor may be entitled in its capacity as a member of the Subsidiary
       Guarantor by way of distribution, return of capital or otherwise;

                     (v) any other claim which the Pledgor now has or may in the
       future acquire in its capacity as a member of the Subsidiary Guarantor
       against the Subsidiary Guarantor and its property; and

                     (vi) all proceeds, products and accessions of and to any of
       the property described in the preceding clauses (i) through (v).

              (b) As used herein, the term "proceeds" shall be construed in its
broadest sense and shall include whatever is received or receivable when any of
the Membership Interests, or any proceeds thereof, are sold, collected,
exchanged or otherwise disposed of, whether voluntarily or involuntarily, and
shall include, without limitation, all rights to payment, including interest and
premiums, with respect to any of the Membership Interests or any proceeds
thereof.

       Section 2.2 Delivery of Certificates and Instruments. All certificates or
instruments representing or evidencing the Membership Interests shall be
delivered

                                        4

<PAGE>   9
to and held by or on behalf of the Collateral Agent pursuant hereto and shall be
in suitable form for transfer by delivery and shall be accompanied by duly
executed instruments of transfer or assignment in blank in the form as attached
as Exhibit A hereto, all in form and substance satisfactory to the Collateral
Agent. The Collateral Agent shall have the right, at any time following the
occurrence and during the continuation of an Event of Default, in its discretion
and without notice to the Pledgor, to transfer to or to register in its name or
in the name of any of its nominees any or all of the Membership Interests. Upon
the occurrence and during the continuance of an Event of Default, the
Collateral Agent shall have the right to exchange certificates or instruments
representing or evidencing any of the Membership Interests for certificates or
instruments of smaller or larger denominations.

      Section 2.3 Pledgor's Rights.

              (a) Distributions. Unless a Trigger Event shall have occurred, the
Pledgor shall be entitled to receive and retain any and all distributions paid
in respect of the Membership Interests (whether in cash or other property) in
compliance with the terms of the other Project Documents; provided, however,
that any and all

                     (i) distributions paid or payable in respect of the
      Membership Interests (whether paid in cash, securities or other property)
      in connection with (A) any partial or total liquidation or dissolution of
      the Subsidiary Guarantor, (B) any distribution of capital of the
      Subsidiary Guarantor, (C) any recapitalization or reclassification of the
      capital of the Subsidiary Guarantor and (D) any reorganization of the
      Subsidiary Guarantor, and

                     (ii) property (whether cash, securities or other property)
      paid, payable or otherwise distributed in redemption of, or in exchange
      for, the property described in clause (i) immediately above,

shall be, and shall be forthwith delivered to the Collateral Agent to hold as,
Pledged Collateral and shall, if received by the Pledgor, be received in trust
for the benefit of the Collateral Agent, be segregated from the other property
or funds of the Pledgor, be forthwith delivered to the Collateral Agent as
Pledged Collateral in the same form as so received (with any necessary
endorsement). Upon the occurrence of a Trigger Event, all rights of the Pledgor
to receive the distributions which it would otherwise be authorized to receive
and retain pursuant to the preceding sentence shall cease, and all such rights
shall thereupon become vested in the Collateral Agent which shall

                                       5
<PAGE>   10

thereupon have the sole right to receive and hold as Pledged Collateral such
distributions.

              (b) Other Rights. Unless a Trigger Event shall have occurred, the
Pledgor shall be entitled to exercise all voting and other rights with respect
to the Membership Interests; provided, however, that no vote shall be cast,
right exercised or other action taken which would knowingly have a Material
Adverse Effect or which would knowingly be materially inconsistent with or
knowingly result in any violation of any provision of this Agreement or any
other Finance Document unless so required by law. Upon the occurrence of a
Trigger Event and upon election by the Collateral Agent, all voting and other
rights of the Pledgor with respect to the Membership Interests which the Pledgor
would otherwise be entitled to exercise pursuant to the terms of this Agreement
shall cease, and all such rights shall be vested in the Collateral Agent which
shall thereupon have the sole right to exercise such rights.

              (c) Turnover. All distributions and other amounts which are
received by the Pledgor contrary to the provisions of this Agreement shall be
received in trust for the benefit of the Collateral Agent, shall be segregated
from other funds of the Pledgor and shall be forthwith paid over to the
Collateral Agent as Pledged Collateral in the same form as so received (with
any necessary endorsement).

      Section 2.4 Secured Parties Not Liable. Notwithstanding any other
provision contained in this Agreement, the Pledgor shall remain liable under the
Operating Agreement to observe and perform all of the conditions and obligations
to be observed and performed by the Pledgor thereunder. None of the Collateral
Agent, any other Secured Party or any of their respective directors, officers,
employees, affiliates or agents shall have any obligations or liability under or
with respect to any Pledged Collateral by reason of or arising out of this
Agreement, except as set forth in Section 9-207 of the UCC as in effect from
time to time in the State of New York, or the receipt by the Collateral Agent of
any payment relating to any Pledged Collateral, nor shall any of the Collateral
Agent, any other Secured Party or any of their respective directors, officers,
employees, affiliates or agents be obligated in any manner to (a) perform any of
the obligations of the Pledgor under or pursuant to the Operating Agreement or
any other agreement to which the Pledgor is a party, (b) make any payment or
inquire as to the nature or sufficiency of any payment or performance with
respect to any Pledged Collateral, (c) present or file any claim or collect the
payment of any amounts or take any action to enforce any performance with
respect to the Pledged Collateral or (d) take any other action whatsoever with

                                       6

<PAGE>   11

respect to the Pledged Collateral, in each case, other than as required under
this Agreement and the other Security Documents.

      Section 2.5 Attorney-in-Fact. (a) The Pledgor hereby appoints the
Collateral Agent, on behalf of the Secured Parties, or any Person, officer or
agent whom the Collateral Agent may designate, as its true and lawful
attorney-in-fact and proxy, with full irrevocable power and authority in the
place and stead of the Pledgor and in the name of the Pledgor or in its own
name, at the Pledgor's reasonable cost and expense, from time to time in the
Collateral Agent's reasonable discretion to take any action and to execute any
instrument which the Collateral Agent may reasonably deem necessary or advisable
to enforce its rights under this Agreement, including, without limitation,
authority to receive, endorse and collect all instruments made payable to the
Pledgor representing any distribution, interest payment or other payment in
respect of the Pledged Collateral or any part thereof to be paid over to the
Collateral Agent pursuant to Section 2.3(c) and to give full discharge for the
same.

              (b) The Pledgor hereby ratifies all that said attorney shall
lawfully do or cause to be done by virtue hereof, in each case pursuant to the
powers granted hereunder. The Pledgor hereby acknowledges and agrees that the
Collateral Agent shall have no fiduciary duties to the Pledgor and the Pledgor
hereby waives any claims or rights of a beneficiary of a fiduciary relationship
hereunder.

      Section 2.6 Collateral Agent May Perform. If the Pledgor fails to perform
any agreement contained herein after receipt of a written request to do so from
the Collateral Agent, the Collateral Agent may (but shall not be obligated to)
itself perform, or cause performance of, such agreement, and the reasonable
expenses of the Collateral Agent, including the reasonable fees and expenses of
its counsel, incurred in connection therewith shall be payable by the Pledgor
under Section 5.5; provided that if a Bankruptcy Event shall have occurred with
respect to the Pledgor, the written request described in this Section 2.6 shall
not be required and shall be deemed to have been delivered upon the failure of
the Pledgor to perform such agreement.

      Section 2.7 Reasonable Care. The Collateral Agent shall be deemed to have
exercised reasonable care in the custody and preservation of the Pledged
Collateral in its possession if the Pledged Collateral is accorded treatment
substantially equivalent to that which the Collateral Agent accords its own
property of the type of which the Pledged Collateral consists, it being
understood that the Collateral Agent shall have no responsibility for (a)
ascertaining or taking action with respect to calls, conver-

                                       7

<PAGE>   12

sions, exchanges, maturities, tenders or other matters relative to any Pledged
Collateral, whether or not the Collateral Agent has or is deemed to have
knowledge of such matters, or (b) taking any necessary steps to preserve rights
against any parties with respect to any Pledged Collateral.

      Section 2.8 Security Interest Absolute. All rights of the Collateral Agent
and security interests hereunder, and all obligations of the Pledgor hereunder,
shall be absolute and unconditional irrespective of:

              (a) any lack of validity or enforceability of any of the Finance
      Documents or any other agreement or instrument relating thereto;

              (b) any change in the time, manner or place of payment of, or in
      any other term of, all or any of the Secured Obligations, or any other
      amendment or waiver of or any consent to any departure from the Finance
      Documents or any other agreement or instrument relating thereto;

              (c) any exchange, release or non-perfection of any other
      collateral, or any release or amendment or waiver of or consent to any
      departure from any guaranty, for all or any of the Secured Obligations; or

              (d) any other circumstance which might otherwise constitute a
      defense available to, or a discharge of, the Pledgor, except as otherwise
      provided herein.

      Section 2.9 Effective as a Financing Statement. This Agreement shall also
be effective as a Financing Statement covering any Pledged Collateral and may be
filed in any appropriate filing or recording office. A carbon, photographic,
facsimile or other reproduction of this Agreement or of any Financing Statement
relating to this Agreement shall be sufficient as a Financing Statement for any
of the purposes referred to in the preceding sentence.

                                   ARTICLE 3
                         REPRESENTATIONS AND WARRANTIES

      The Pledgor represents and warrants, as of the date of this Agreement and
the Closing Date, as follows, which representations and warranties shall survive
the execution and delivery of this Agreement and the making and repayment of the
Secured Obligations:

                                       8
<PAGE>   13
       Section 3.1 Necessary Filings. All filings, registrations and recordings
necessary or appropriate to create, preserve, protect and perfect the security
interest granted to the Collateral Agent hereby in respect of the Pledged
Collateral have been accomplished and the security interest granted to the
Collateral Agent pursuant to this Agreement in and to the Pledged Collateral
constitutes (i) a valid and enforceable perfected security interest therein as
collateral security for the Secured Obligations to the extent that a security
interest may be perfected by filing and/or the other actions specified herein,
and (ii) is prior to all other Liens on the Pledged Collateral in existence on
the date hereof.

       Section 3.2 No Liens. The Pledgor is the owner of all of its right, title
and interest in the Pledged Collateral pledged by it hereunder free from any
Lien or other right, title or interest of any Person other than the Lien created
pursuant to this Agreement and other than Permitted Liens.

       Section 3.3 Other Financing Statements. There is no Financing Statement
(or similar statement or instrument of registration under the law of any
jurisdiction) executed by the Pledgor, or, to the knowledge of the Pledgor after
due inquiry, by any other Person covering or purporting to cover any interest of
any kind in the Pledged Collateral hereunder, except Financing Statements filed
or to be filed in respect of and covering the security interests granted hereby
by the Pledgor.

       Section 3.4 Chief Executive Office. The chief executive office of the
Pledgor and the office where the Pledgor keeps its records concerning the
Pledged Collateral is located at: 1221 Nicollet Mall, Suite 700, Minneapolis,
Minnesota 55403.

       Section 3.5 Consents, etc. No consent, authorization, approval or other
action by, and no notice to or filing with, any governmental authority is
required either (i) for the pledge by the Pledgor of the Pledged Collateral
pursuant to this Agreement or for the due execution, delivery or performance of
this Agreement by the Pledgor, or (ii) for the exercise by the Collateral Agent
of the voting or other rights provided for in this Agreement or of the remedies
in respect of the Pledged Collateral pursuant to this Agreement, except as may
be required in connection with the disposition of the Pledged Collateral by laws
affecting the offering and sale of securities generally.

                                       9
<PAGE>   14

                                    ARTICLE 4
                                    COVENANTS

       The Pledgor hereby covenants and agrees from and after the date of this
Agreement until the termination of this Agreement in accordance with the
provisions of Section 6.3:

       Section 4.1 Sale of Pledged Collateral. Except as otherwise permitted by
the Finance Documents, the Pledgor shall not sell or otherwise dispose of, or
grant any option or warrant with respect to, any of the Pledged Collateral.

       Section 4.2 No Other Liens. The Pledgor shall not create, incur or permit
to exist, shall defend the Pledged Collateral owned by it against and shall take
such other action as is reasonably necessary to remove, any Lien or claim on or
to the Pledged Collateral, other than the Lien created pursuant to this
Agreement, and shall defend the right, title and interest of the Collateral
Agent in and to the Pledged Collateral against the claims and demands of all
Persons whomsoever.

       Section 4.3 Chief Executive Office. The Pledgor shall not establish a new
location for its chief executive office or change its name until (i) it has
given to the Collateral Agent not less than thirty (30) days prior written
notice of its intention so to do, clearly describing such new location or
specifying such new name, as the case may be, and (ii) with respect to such new
location or such new name, as the case may be, it shall have taken all action,
satisfactory to the Collateral Agent, to maintain the security interest of the
Collateral Agent in the Pledged Collateral intended to be granted hereby at all
times fully perfected and in full force and effect.

       Section 4.4 Supplements; Further Assurances, etc. The Pledgor shall at
any time and from time to time, at the reasonable expense of the Pledgor,
promptly execute and deliver all further instruments and documents, and take all
further action, that may be necessary or desirable, or that the Collateral Agent
may reasonably request, in order to perfect and protect any security interest
granted or purported to be granted hereby or to enable the Collateral Agent to
exercise and enforce its rights and remedies hereunder with respect to any
Pledged Collateral.

       Section 4.5 Amendment of Operating Agreement. Except as otherwise
specifically provided in the Finance Documents, the Pledgor shall not, without
the prior written consent of the Collateral Agent, acting upon directions from
the Secured Parties pursuant to the Intercreditor Agreement, or as otherwise
expressly.

                                       10
<PAGE>   15

provided herein, agree to or permit (a) the cancellation or termination of the
Operating Agreement, except upon the expiration of the stated term thereof, or
(b) any amendment, supplement, or modification of, or waiver with respect to any
of the provisions of, the Operating Agreement, except to the extent that such
amendment, supplement, modification or waiver would not reasonably be expected
to result in a Material Adverse Effect.

       Section 4.6 Certificates and Instruments. The Pledgor shall deliver all
certificates or other documents representing the Pledged Collateral to the
Collateral Agent with all necessary instruments of transfer or assignment duly
indorsed in blank. In the event the Pledgor obtains possession of any other
certificates, or other securities or instruments forming a part of the Pledged
Collateral, the Pledgor shall promptly deliver same to the Collateral Agent
together with all necessary instruments of transfer or assignment duly indorsed
in blank. Prior to any such delivery, any Pledged Collateral in the Pledgor's
possession shall be held by the Pledgor in trust for the Collateral Agent.

       Section 4.7 Financing Statements. The Pledgor shall sign and deliver to
the Collateral Agent and the other Secured Parties such Financing Statements (or
similar statements or instruments of registration under the law of any
jurisdiction), as are necessary under applicable law to establish and maintain
the security interests contemplated hereunder as valid, enforceable, first
priority security interests as provided herein and the other rights and security
contemplated herein, all in accordance with the UCC as enacted in any and all
relevant jurisdictions or any other applicable law. The Pledgor shall pay any
applicable filing fees and related expenses. The Pledgor authorizes the
Collateral Agent to file any such Financing Statements (or similar statements or
instruments of registration under the law of any jurisdiction) without the
signature of the Pledgor.

       Section 4.8 Records; Statements and Schedules. The Pledgor shall keep and
maintain, at its own cost and expense, records of the Pledged Collateral owned
by it, including, but not limited to, records of all payments received with
respect thereto, and upon reasonable notice, and during normal business hours,
the Pledgor shall make the same available to the Collateral Agent for inspection
at the Pledgor's chief executive office, at the Pledgor's own cost and expense.
The Pledgor shall furnish to the Collateral Agent from time to time statements
and schedules further identifying and describing the Pledged Collateral and such
other reports in connection with the Pledged Collateral as the Collateral Agent
may reasonably request, all in reasonable detail.

                                       11
<PAGE>   16

       Section 4.9 Improper Distributions. Notwithstanding any other provision
contained in this Agreement, the Pledgor shall not accept any distributions,
dividends or other payments (or any collateral in lieu thereof) in respect of
the Pledged Collateral, except to the extent the same are expressly permitted
by the terms of this Agreement and the other Finance Documents.

       Section 4.10 Bankruptcy. The Pledgor shall not authorize or permit the
Subsidiary Guarantor to (a) commence a voluntary case or other proceeding
seeking liquidation, reorganization or other relief with respect to the
Subsidiary Guarantor or the Subsidiary Guarantor's debts under any Bankruptcy
Law now or hereafter in effect or seeking the appointment of a trustee,
receiver, liquidator, custodian or other similar official of the Subsidiary
Guarantor or any substantial part of the Subsidiary Guarantor's property, (b)
consent to any such relief or to the appointment of or taking possession by any
such official in an involuntary case or other proceeding commenced against the
Subsidiary Guarantor or (c) make a general assignment for the benefit of the
Subsidiary Guarantor's creditors. The Pledgor shall not commence or join with
any other Person (other than the Collateral Agent and the other Secured Parties)
in commencing any proceeding against the Subsidiary Guarantor under any
Bankruptcy Law now or hereafter in effect in any jurisdiction.

                                    ARTICLE 5
                  EXERCISE OF REMEDIES UPON AN EVENT OF DEFAULT

_______The provisions of this Article 5 shall apply only upon the occurrence and
during the continuance of an Event of Default.

       Section 5.1 Remedies Generally. If an Event of Default shall have
occurred and be continuing, the Collateral Agent, upon directions from the
Secured Parties pursuant the Intercreditor Agreement, or as otherwise expressly
provided herein, may exercise, in addition to all other rights and remedies
granted in this Agreement and in any other instrument or agreement securing,
evidencing or relating to the Secured Obligations, all rights and remedies of a
secured party under the UCC in effect from time to time in any relevant
jurisdiction and all other rights and remedies available at law or in equity.

       Section 5.2 Sale of Pledged Collateral. (a) Without limiting the
generality of Section 5.1, the Collateral Agent, upon directions from the
Secured Parties pursuant to the Intercreditor Agreement, or as otherwise
expressly provided herein,

                                       12

<PAGE>   17

may, with notice as required by applicable law, sell the Pledged Collateral or
any part thereof in one or more parcels at public or private sale or at any of
the Collateral Agent's corporate trust office or elsewhere, for cash, on credit
or for future delivery, and at such price or prices and upon such other terms as
the Collateral Agent may reasonably deem commercially reasonable, irrespective
of the impact of any such sales on the market price of the Pledged Collateral at
any such sale. Each purchaser at any such sale shall hold the property sold
absolutely free from any claim or right on the part of the Pledgor, and the
Pledgor hereby waives (to the extent permitted by law) all rights of redemption,
stay and/or appraisal which it now has or may at any time in the future have
under any rule of law or statute now existing or hereafter enacted. The Pledgor
agrees that, to the extent notice of sale shall be required by law, at least ten
(10) days' notice to the Pledgor of the time and place of any public sale or the
time after which any private sale is to be made shall constitute reasonable
notification. The Collateral Agent shall not be obligated to make any sale of
Pledged Collateral regardless of notice of sale having been given. The
Collateral Agent may adjourn any public or private sale from time to time by
announcement at the time and place fixed therefor, and such sale may, without
further notice, be made at the time and place to which it was so adjourned.
Assuming that such sales are made in compliance with federal and state
securities laws and the UCC, the Collateral Agent shall incur no liability as a
result of the sale of the Pledged Collateral, or any part thereof, at any public
or private sale. The Pledgor hereby waives any claims against the Collateral
Agent arising by reason of the fact that the price at which any Pledged
Collateral may have been sold at such a private sale, if commercially
reasonable, was less than the price which might have been obtained at a public
sale, even if the Collateral Agent accepts the first offer received and does not
offer the Pledged Collateral to more than one offeree.

       (b) The Pledgor recognizes that the Collateral Agent, upon directions
from the Secured Parties pursuant to the Intercreditor Agreement, or as
otherwise expressly provided herein, may elect to sell all or any part of the
Pledged Collateral to one or more purchasers in privately negotiated
transactions in which the purchasers will be obligated to agree, among other
things, to acquire the Pledged Collateral for their own account, for investment
and not with a view to the distribution or resale thereof. The Pledgor
acknowledges that any such private sales may be at prices and on terms less
favorable than those obtainable through a public sale (including, without
limitation, a public offering made pursuant to a registration  statement under
the Securities Act of 1933, as amended (the "Securities  Act")), and the Pledgor
and the Collateral Agent agree that such private sales shall be made in a
commercially reasonable manner and that the Collateral Agent has no obligation
to engage in

                                       13
<PAGE>   18

public sales and no obligation to delay sale of any Pledged Collateral to permit
the issuer thereof to register the Pledged Collateral for a form of public sale
requiring registration under the Securities Act. If the Collateral Agent, upon
directions from the Secured Parties pursuant to the Intercreditor Agreement, or
as otherwise expressly provided herein, determines to exercise its right to sell
any or all of the Pledged Collateral, upon written request, the Pledgor shall,
from time to time, furnish to the Collateral Agent all such information as the
Collateral Agent may request in order to determine the number of shares and
other instruments included in the Pledged Collateral which may be sold by the
Collateral Agent as exempt transactions under the Securities Act and rules of
the Securities and Exchange Commission thereunder, as the same are from time to
time in effect.

       Section 5.3 Purchase of Pledged Collateral. The Collateral Agent may be a
purchaser of the Pledged Collateral or any part thereof or any right or interest
therein at any sale thereof, whether pursuant to foreclosure, power of sale or
otherwise hereunder and the Collateral Agent may apply the purchase price to the
payment of the Secured Obligations. Any purchaser of all or any part of the
Pledged Collateral shall, upon any such  purchase, acquire good title to the
Pledged Collateral so purchased, free of the security interests created by this
Agreement.

       Section 5.4 Application of Proceeds. The Collateral Agent shall apply any
proceeds from time to time held by it and the net proceeds of any collection,
recovery, receipt, appropriation, realization or sale with respect to the
Pledged Collateral in accordance with Section 5.3 of the Intercreditor
Agreement. For avoidance of doubt, it is understood that the Subsidiary
Guarantor shall remain liable to the extent of any deficiency between the amount
of proceeds of the Pledged Collateral and the aggregated amount of the Secured
Obligations in accordance with the Finance Documents.

                                   ARTICLE 6
                            MISCELLANEOUS PROVISIONS

       Section 6.1 Notices.  Unless otherwise specifically herein provided, all
notices required or permitted under the terms and provisions hereof shall be in
writing and any such notice shall become effective if given in accordance with
the provisions of Section 12.5 of the Indenture

                                       14
<PAGE>   19

       Section 6.2 Continuing Security Interest. This Agreement shall create a
continuing security interest in the Pledged Collateral until the release thereof
pursuant to Section 6.3.

       Section 6.3 Release. (a) Upon the indefeasible payment in full of the
Secured Obligations in cash or cash equivalents and the termination of all
commitments of the Secured Parties under the Finance Documents, the Collateral
Agent, upon the written request, and at the expense, of the Pledgor, shall
execute and deliver all such documentation necessary to release the security
interest created pursuant to this Agreement.

       (b) Upon the sale or disposition of any portion of the Pledged Collateral
permitted pursuant to the terms of the Finance Documents, including, but not
limited to, any Permitted Asset Sale, the purchaser of such portion of the
Pledged Collateral shall, upon such purchase, acquire good title to the Pledged
Collateral so purchased, free of the security interests created by this
Agreement. The Collateral Agent, upon the written request, and at the expense,
of the Pledgor, shall execute and deliver all such documentation necessary to
evidence such release of the security interest created in such Pledged
Collateral pursuant to this Agreement.

       Section 6.4 Reinstatement. This Agreement shall continue to be effective
or be reinstated, as the case may be, if at any time any amount received by the
Collateral Agent or any other Secured Party hereunder or pursuant hereto is
rescinded or must otherwise be restored or returned by the Collateral Agent or
such Secured Party upon a Bankruptcy Event of the Pledgor or the Subsidiary
Guarantor or upon the appointment of any intervenor or conservator of, or
trustee or similar official for, the Pledgor or the Subsidiary Guarantor or any
substantial part of the Pledgor's or the Subsidiary Guarantor's assets, or upon
the entry of an order by any court avoiding the payment of such amount, or
otherwise, all as though such payments had not been made.

       Section 6.5 Independent Security. The security provided for in this
Agreement shall be in addition to and shall be independent of every other
security which the Secured Parties may at any time hold for any of the Secured
Obligations hereby secured, whether or not under the Finance Documents. The
execution of any other Finance Document shall not modify or supersede the
security interest or any rights or obligations contained in this Agreement and
shall not in any way affect, impair or invalidate the effectiveness and validity
of this Agreement or any term or condition hereof. The Pledgor hereby waives its
right to plead or claim in any court that the

                                       15
<PAGE>   20

execution of any other Finance Document is a cause for extinguishing,
invalidating, impairing or modifying the effectiveness and validity of this
Agreement or any term or condition contained herein. The Collateral Agent shall
be at liberty to accept further security from the Pledgor or from any third
party and/or release such security without notifying the Pledgor and without
affecting in any way the obligations of the Pledgor under the Finance Documents.
The Collateral Agent, upon written directions from the Secured Parties pursuant
to the Intercreditor Agreement, or as otherwise expressly provided herein,
shall determine if any security conferred upon the Collateral Agent under the
Finance Documents shall be enforced by the Collateral  Agent, as well as the
sequence of securities to be so enforced.

       Section 6.6  Amendments. No waiver, amendment, modification or
termination of any provision of this Agreement, or consent to any departure by
the Pledgor therefrom, shall in any event be effective without the prior written
consent of the Collateral Agent, acting upon written directions from the Secured
Parties pursuant to the Intercreditor Agreement, or as otherwise expressly
provided herein, and none of the Pledged Collateral shall be released without
the written consent of the Collateral Agent, acting upon directions from the
Secured Parties pursuant to the Intercreditor Agreement, or as otherwise
expressly provided herein. Any such waiver or consent shall be effective only in
the specific instance and for the specific purpose for which given.

       Section 6.7 Successors and Assigns. This Agreement shall be binding upon
the Pledgor and its successors and assigns and shall inure to the benefit of the
Collateral Agent and the other Secured Parties and their respective successors
and assigns. The Pledgor may not assign or otherwise transfer any of its rights
or obligations under this Agreement without the written consent of the
Collateral Agent, acting upon written directions from the Secured Parties
pursuant to the Intercreditor Agreement, or as otherwise expressly provided
herein.

       Section 6.8  Third Party Beneficiaries.  The agreements of the parties
hereto are intended to benefit the Secured Parties and their respective
successors and assigns.

       Section 6.9  Conflict with Indenture. In case of a conflict between any
provision of this Agreement and any provision of the Indenture, the provisions
of the Indenture shall control and govern. No such conflict shall be deemed to
exist thereby because this Agreement imposes greater obligations on the
Subsidiary Guarantor or the Pledgor than the Indenture.

                                       16

<PAGE>   21

       Section 6.10 Survival. All agreements, statements, representations and
warranties made by the Pledgor herein or in any certificate or other instrument
delivered by the Pledgor or on its behalf under this Agreement shall be
considered to have been relied upon by the Collateral Agent and the other
Secured Parties and shall survive the execution and delivery of this Agreement
and the other Finance Documents until termination thereof or the indefeasible
payment in full in cash or cash equivalents of all of the Secured Obligations
and the termination of all commitments of the Secured Parties under the Finance
Documents regardless of any investigation made by the Collateral Agent or the
other Secured Parties or made on their behalf.

       Section 6.11 No Waiver; Remedies Cumulative. No failure or delay on the
part of the Collateral Agent in exercising any right, power or privilege
hereunder and no course of dealing between the Pledgor and the Collateral Agent
shall operate as a waiver thereof; nor shall any single or partial exercise of
any right, power or privilege hereunder preclude any other or further exercise
thereof or the exercise of any other right, power or privilege hereunder or
thereunder. The rights and remedies herein expressly provided are cumulative and
not exclusive of any rights or remedies which the Collateral Agent would
otherwise have.

       Section 6.12 Counterparts. This Agreement may be executed in any number
of counterparts and by the different parties hereto on separate counterparts,
each of which when so executed and delivered shall be an original, but all of
which shall together constitute one and the same instrument.

       Section 6.13 Headings Descriptive. The headings of the several Sections
and subsections of this Agreement are inserted for convenience only and shall
not in any way affect the meaning or construction of any provision of this
Agreement.

       Section 6.14 Severability. In case any provision contained in or
obligation under this Agreement shall be invalid, illegal or unenforceable in
any jurisdiction, the validity, legality and enforceability of the remaining
provisions or obligations, or of such provision or obligation in any other
jurisdiction, shall not in any way be affected or impaired thereby.

       Section 6.15 Governing Law; Submission to Jurisdiction; Waiver of Jury
Trial.

              (a) THIS AGREEMENT IS A CONTRACT MADE UNDER THE LAWS OF THE STATE
OF NEW YORK OF THE UNITED STATES AND

                                       17
<PAGE>   22

SHALL FOR ALL PURPOSES BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS
OF SUCH STATE WITHOUT REGARD TO THE CONFLICT OF LAW RULES THEREOF (OTHER THAN
SECTION 5-1401 OF THE NEW YORK GENERAL OBLIGATIONS LAW).

              (b) Any legal action or proceeding against the Pledgor with
respect to this Agreement may be brought in the courts of the State of New York
in the County of New York or of the United States for the Southern District of
New York and, by execution and delivery of this Agreement, the Pledgor hereby
irrevocably submits and accepts for itself and in respect of its property,
generally and unconditionally, the jurisdiction of the aforesaid courts. The
Pledgor agrees that a judgment, after exhaustion of all available appeals, in
any such action or proceeding shall be conclusive and binding upon the Pledgor
and may be enforced in any other jurisdiction, by a suit upon such judgment, a
certified copy of which shall be conclusive evidence of the judgment. The
Pledgor hereby irrevocably designates, appoints and empowers CT Corporation
System with offices on the date hereof at 111 Eighth Avenue, New York, N.Y.
10011, as its designee, appointee and agent to receive, accept and acknowledge
for and on its behalf, and in respect of its property, service of any and all
legal process, summons, notice and documents which may be served in any such
action or proceeding. If for any reason such designee, appointee and agent shall
cease to be available to act as such agent, the Pledgor agrees to designate a
new designee, appointee and agent in New York City on the terms and for the
purposes of this provision satisfactory to the Collateral Agent. The Pledgor
further irrevocably consents to the service of process out of any of the
aforementioned courts in any such action or proceeding by the mailing of copies
thereof by registered or certified mail, postage prepaid, to the Pledgor at its
address referred to in Section 6.1, such service to become effective thirty (30)
days after such mailing. Nothing herein shall affect the right of the Collateral
Agent or any other Person to serve process in any other manner permitted by law
or to commence legal proceedings or otherwise proceed against the Pledgor in any
other jurisdiction.

              (c) The Pledgor hereby irrevocably waives any objection which it
may now or hereafter have to the laying of venue of any of the aforesaid actions
or proceedings arising out of or in connection with this Agreement in the courts
referred to in clause (b) above and hereby further irrevocably waives and agrees
not to plead or claim in any such court that any such action or proceeding
brought in any such court has been brought in an inconvenient forum.

                                       18
<PAGE>   23

              (d) WITH REGARD TO THIS AGREEMENT, EACH PARTY HERETO HEREBY WAIVES
THE RIGHT TO A TRIAL BY JURY.

       Section 6.16 Entire Agreement. This Agreement, together with any other
agreement executed in connection herewith, is intended by the parties as a final
expression of their agreement as to the matters covered hereby and is intended
as a complete and exclusive statement of the terms and conditions thereof.

       Section 6.17 Independent Obligations. The Pledgor's obligations under
this Agreement are independent of those of the Subsidiary Guarantor. The
Collateral Agent may bring a separate action against the Pledgor without first
proceeding against the Subsidiary Guarantor or any other Person or any other
security held by the Collateral Agent and without pursuing any other remedy.

       Section 6.18 Limitation of Liability. The provisions of Section 12.11 of
the Indenture shall apply to this Agreement.

            [THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK]

                                       19
<PAGE>   24

       IN WITNESS WHEREOF, the parties hereto have caused this Pledge and
Security Agreement to be duly executed and delivered by their officers thereunto
duly authorized as of the date first above written.

                                 NRG SOUTH CENTRAL GENERATING LLC

                                 By:   /s/ Craig A. Mataczynski
                                       ----------------------------
                                       Name:  Craig A. Mataczynski
                                       Title: President

                                 THE CHASE MANHATTAN BANK,
                                 solely in its capacity as the Collateral Agent

                                 By:   /s/ Annette M. Marsula
                                       ----------------------------
                                       Name:  Annette M. Marsula
                                       Title: Vice President

                                       20
<PAGE>   25
                                                                   Schedule I to
                                                                      Pledge and
                                                              Security Agreement

                                  Certificates

Certificate No. 3 representing a 100% interest in Louisiana Generating LLC.

                                   Sch. I - 1

<PAGE>   26

                                                                    Exhibit A to
                                                                      Pledge and
                                                              Security Agreement

                      ASSIGNMENT SEPARATE FROM CERTIFICATE

       FOR VALUE RECEIVED, NRG SOUTH CENTRAL GENERATING LLC hereby assigns and
transfers unto ___________________________ [ ] membership interests of
LOUISIANA GENERATING LLC, a Delaware limited liability company (the "Limited
Liability Company"), standing in its name on the books of the Limited Liability
Company, which is represented by Certificate No. [ ], authorizing any officer
of the Limited Liability Company to transfer said membership interests on the
books of the within named Limited Liability Company with full power of
substitution.

DATED as of __________ ___, 20000

                        NRG SOUTH CENTRAL GENERATING LLC
                        a Delaware limited liability company

                        By:
                           ------------------------------------

                                   Sch. I - 2

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