<PAGE>
 
                                                                   EXHIBIT 10.13
                  MASTER LOAN AND SECURITY AGREEMENT NO. 3963


DEBTOR:   PSINet Inc.                SECURED PARTY:   Charter Financial, Inc.
          510 Huntmar Park Drive                      153 East 53/rd/ Street
          Herndon, VA  20170                          New York, NY 10022

In consideration of the mutual covenants set forth herein, the above named
Debtor and the above named Secured Party hereby enter into this Master Loan and
Security Agreement and agree to the terms and conditions set forth herein.  Each
Loan Schedule which may be executed by Debtor and Secured Party from time to
time pursuant to this Master Loan and Security Agreement shall be deemed to be a
separate loan transaction incorporating all of the terms and conditions of this
Master Loan and Security Agreement.  References in this Master Loan and Security
Agreement to "Agreement", "hereunder" and "herein" shall mean a Loan Schedule
which incorporates this Master Loan and Security Agreement.

     1.  LOAN SCHEDULES.  Debtor shall evidence its agreement to enter into each
Agreement incorporating the terms hereof by executing and delivering to Secured
Party a Loan Schedule in the form annexed hereto as Exhibit 1.  Debtor's
execution of a Loan Schedule shall obligate Debtor to make all of the payments
set forth in the Schedule of Obligations as set forth in the Loan Schedule.
The Loan Schedule shall set forth the amount of the Loan, the Term of the Loan,
the number of payments to be made and the amount and dates upon which such
payments are due.  The Loan Schedule shall also set forth the Time Balance which
means the aggregate amount of all payments which are payable under the Agreement
evidenced by such Loan Schedule.  Secured Party shall have no obligation to
enter into or accept any Loan Schedule and no Loan Schedule shall be binding
upon Secured Party until accepted by Secured Party which acceptance shall be
evidenced only by the execution  of such Loan Schedule by Secured Party.
 
     2.  GRANT OF SECURITY INTEREST.  Debtor hereby grants to Secured Party a
security interest in the personal property referred to and/or described in each
Loan Schedule (hereinafter with all renewals, substitutions and replacements and
all parts, repairs, improvements, additions and accessories incorporated therein
or affixed thereto referred to as the "Equipment"), together with any and all
proceeds thereof and any and all insurance policies and proceeds with respect
thereto.
 
     3.  OBLIGATIONS SECURED. The aforesaid security interest is granted by
Debtor as security for (a) the payment of the Time Balance (as set forth in the
Loan Schedule) and the payment and performance of all other indebtedness and
obligations now or hereafter owing by Debtor to Secured Party, of any and every
kind and description under the Agreement evidenced by such Loan Schedule, and
any and all renewals and extensions of the foregoing, and all interest, fees,
charges, expenses and attorneys' fees accruing or incurred in connection with
any of the foregoing (all of which Time Balance, indebtedness and obligations
are hereinafter referred to as the "Liabilities") and (b) the payment and
performance of all other indebtedness and obligations now or hereafter owing by
Debtor to Secured Party, of any and every kind and description, howsoever
arising or evidenced including without limitation those arising under other Loan
Schedules, (all of which indebtedness and obligations are hereinafter referred
to as the "Other Liabilities"). Subject to Paragraph 16, any nonpayment of any
installment or other amounts within ten days of when due hereunder shall result
in the obligation on the part of Debtor promptly to pay also an amount equal to
five percent (5%), (or the maximum rate permitted by law, whichever is less) of
the installment or other amounts overdue.
 
     4.  DISCLAIMER OF WARRANTIES. DEBTOR ACKNOWLEDGES THAT SECURED PARTY MAKES
NO WARRANTIES, EXPRESS OR IMPLIED, IN RESPECT OF THE EQUIPMENT, INCLUDING,
WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR OF FITNESS FOR ANY
PARTICULAR PURPOSE. Secured Party shall not be liable to Debtor for any loss,
damage or expense of any kind or nature caused, directly or indirectly, by any
Equipment secured hereunder or the use or maintenance thereof or the failure of
operation thereof, or the repair, service or adjustment thereof, or by any delay
or failure to provide any such maintenance, repairs, service or adjustment, or
by any interruption of service or loss of use thereof or for any loss of
business howsoever caused. The Equipment shall be shipped directly to Debtor by
the supplier thereof and Debtor agrees to accept such delivery. No defect or
unfitness of the Equipment, nor any failure or
<PAGE>
 
delay on the part of the manufacturer or the shipper of the Equipment to deliver
the Equipment or any part thereof to Debtor, shall relieve Debtor of the
obligation to pay the Time Balance or any other obligation under this Agreement.
Secured Party shall have no obligation under this Agreement in respect of the
Equipment and shall have no obligation to install, erect, test, adjust or
service the Equipment. Secured Party agrees, so long as there shall not have
occurred and be continuing any Event of Default hereunder or event which with
lapse of time or notice, or both, might become an Event of Default hereunder,
that Secured Party will permit Debtor to enforce in Debtor's own name at
Debtor's sole expense any supplier's or manufacturer's warranty or agreement in
respect of the Equipment to the extent that such warranty or agreement is
assignable.
 
     5.  ASSIGNMENT.  Any transaction evidenced by a Loan Schedule shall be
assignable by Secured Party, and by its assigns, without the consent of Debtor,
but Debtor shall not be obligated to any assignee except upon written notice of
such assignment from Secured Party or such assignee.  Subject to Section 19
hereof, the obligation of Debtor to pay and perform the Liabilities to such
assignee shall be absolute and unconditional and shall not be affected by any
circumstance whatsoever, and such payments shall be made without interruption or
abatement notwithstanding any event or circumstance whatsoever, including,
without limitation, the late delivery, non-delivery, destruction or damage of or
to the Equipment, the deprivation or limitation of the use of the Equipment, the
bankruptcy or insolvency of Secured Party or Debtor or any disaffirmance of this
Agreement by or on behalf of Debtor and notwithstanding any defense, set-off,
recoupment or counterclaim or any other right whatsoever, whether by reason of
breach of this Agreement or of any warranty in respect of the Equipment or
otherwise which Debtor may now or hereafter have against Secured Party, and
whether any such event shall be by reason of any act or omission of Secured
Party (including, without limitation, any negligence of Secured Party) or
otherwise; provided, however, that nothing herein contained shall affect any
right of Debtor to enforce against Secured Party any claim which Debtor may have
against Secured Party in any manner other than by abatement, attachment or
recoupment of, interference with, or set-off, counterclaim or defense against,
the aforementioned payments to be made to such assignee.  Debtor's undertaking
herein to pay and perform the Liabilities to an assignee of Secured Party shall
constitute a direct, independent and unconditional obligation of Debtor to said
assignee.  Said assignee shall have no obligations under this Agreement or in
respect of the Equipment and shall have no obligation to install, erect, test,
adjust or service the Equipment.  Debtor also acknowledges and agrees that any
assignee of Secured Party's interest in this Agreement shall have the right to
exercise all rights, privileges and remedies (either in its own name or in the
name of Secured Party) which by the terms of this Agreement are permitted to be
exercised by Secured Party.
 
     6.  DAMAGE TO OR LOSS OF THE EQUIPMENT; REQUISITION. Debtor assumes and
shall bear the entire risk of loss or damage to the Equipment from any and every
cause, whatsoever. No loss or damage to the Equipment or any part thereof shall
affect any obligation of Debtor with respect to the Liabilities and this
Agreement, which shall continue in full force and effect. Debtor shall advise
Secured Party in writing prompt ly of any item of Equipment lost or damaged and
of the circumstances and extent of such damage. If the Equipment is totally
destroyed, irreparably damaged, lost, stolen or title thereto shall be
requisitioned or taken by any governmental authority under the power of eminent
domain or otherwise, Debtor shall, at the option of Secured Party, replace the
same with like equipment in good repair, condition and working order, or pay to
Secured Party all Liabilities due and to become due (with all future Rentals to
be paid over the term of the Agreement discounted at a rate equal to five
percent (5%)), less the net amount of the recovery, if any, actually received by
Secured Party from insurance or otherwise for such destruction, damage, loss,
theft, requisition or taking. Whenever the Equipment is destroyed or damaged
and, in the sole discretion of Secured Party, such destruction or damage can be
repaired, Debtor shall, at its expense, promptly effect such repairs as Secured
Party shall deem necessary for compliance with clause (a) of paragraph 8 below.
Any proceeds of insurance received by Secured Party with respect to such
reparable damage to the Equipment shall, at the election of Secured Party, be
applied either to the repair of the Equipment by payment by Secured Party
directly to the party completing the repairs, or to the reimbursement of Debtor
for the cost of such repairs; provided, however, that Secured Party shall have
no obligation to make such payment or any part thereof until receipt of such
evidence as Secured Party shall deem satisfactory that such repairs have been
completed and further provided that Secured Party may apply such proceeds to the
payment of any of the Liabilities or the Other Liabilities due if at the time
such proceeds are received by Secured Party there shall have occurred and be
continuing any Event of Default hereunder or any event which with lapse of time
or notice, or both, would
<PAGE>
 
become an Event of Default. Debtor shall, when and as requested by Secured
Party, undertake, by litigation or otherwise, in Debtor's name, the collection
of any claim against any person for such destruction, damage, loss, theft,
requisition or taking, but Secured Party shall not be obligated to undertake, by
litigation or otherwise, the collection of any claim against any person for such
destruction, damage, loss, theft, requisition or taking.
 
     7.  REPRESENTATIONS AND WARRANTIES OF DEBTOR. Debtor represents and
warrants that: it has the right, power and authority to enter into and carry out
the terms and provisions of this Agreement; this Agreement constitutes a valid
obligation of the Debtor and is enforceable in accordance with its terms; and
entering into this Agreement and carrying out its terms and provisions will not
violate the terms or constitute a breach of any other agreement to which Debtor
is a party.

     8.  AFFIRMATIVE COVENANTS OF DEBTOR. Debtor shall (a) cause the Equipment
to be kept in good condition and use the Equipment only in the manner for which
it was designed and intended so as to subject it only to ordinary wear and tear
and cause to be made all needed and proper repairs, renewals and replacements
thereto; (b) maintain at all times property damage, fire, theft and
comprehensive insurance for the full replacement value of the Equipment, with
additional loss payable provisions in favor of Secured Party and any assignee of
Secured Party as their interests may appear, and maintain public liability
insurance in amounts satisfactory to Secured Party, naming Secured Party and any
assignee of Secured Party as insureds with all of said insurance and loss
payable provisions to be in form, substance and amount and written by companies
reasonably approved by Secured Party, and deliver certificate of insurance
policies therefor, or duplicates thereof, to Secured Party; (c) pay or reimburse
Secured Party for any and all taxes, assessments and other governmental charges
of whatever kind or character, however designated (together with any penalties,
fines or interest thereon) levied or based upon or with respect to the
Equipment, the Liabilities or this Agreement or upon the manufacture, purchase,
ownership, delivery, possession, use, storage, operation, maintenance, repair,
return or other disposition of the Equipment, or upon any receipts or earnings
arising therefrom, or for titling or registering the Equipment, or upon the
income or other proceeds received with respect to the Equipment or this
Agreement provided, however, that Debtor shall pay taxes on or measured by the
net income of Secured Party and franchise taxes of Secured Party only to the
extent that such net income taxes or franchise taxes are levied or assessed in
lieu of any other taxes, assessments or other governmental charges hereinabove
described; (d) pay all shipping and delivery charges and other expenses incurred
in connection with the Equipment and pay all lawful claims, whether for labor,
materials, supplies, rents or services, which might or could if unpaid become a
lien on the Equipment; (e) comply in all material respects with all governmental
laws, regulations, requirements and rules, all instructions and warranty
requirements of Secured Party or the manufacturer of the Equipment, and with the
conditions and requirements of all policies of insurance with respect to the
Equipment and this Agreement; (f) mark and identify the Equipment with all
information and in such manner as Secured Party may request from time to time
and replace promptly any such marking or identification which are removed,
defaced or destroyed; (g) at any and all times during business hours upon prior
request by facsimile, grant to Secured Party free access to enter upon the
premises wherein the Equipment shall be located and permit Secured Party to
inspect the Equipment; (h) reimburse Secured Party for all charges, costs and
expenses (including reasonable attorneys' fees) incurred by Secured Party in
defending or protecting its interests in the Equipment, in the attempted
enforcement or enforcement of the provisions of this Agreement or in the
attempted collection or collection of any of the Liabilities; (i) indemnify and
hold any assignee of Secured Party, and Secured Party, harmless from and against
all claims, losses, liabilities, damages, judgments, suits, and all legal
proceedings, and any and all costs and expenses in connection therewith
(including reasonable attorneys' fees) arising out of or in any manner connected
with the manufacture, purchase, ownership, delivery, possession, use, storage,
operation, maintenance, repair, return or other disposition of the Equipment or
with this Agreement, including, without limitation, claims for injury to or
death of persons and for damage to property but excluding any claims resulting
from Secured Party's gross negligence or wilful misconduct, and give Secured
Party prompt notice of any such claim or liability; and (j) maintain a system of
accounts established and administered in accordance with generally accepted
accounting principles and practices consistently applied, and, within sixty (60)
days after the end of each fiscal quarter, deliver to Secured Party a balance
sheet as at the end of such quarter and statement of operations for such
quarter, and, within one hundred and twenty (120) days after the end of each
fiscal year, deliver to Secured
<PAGE>
 
Party a balance sheet as at the end of such year and statement of operations for
such year, in each case prepared in accordance with generally accepted
accounting principles and practices consistently applied and certified by
Debtor's chief financial officer as fairly presenting the financial position and
results of operation of Debtor in accordance with generally accepted accounting
principles, and, in the case of year end financial statements, certified by an
independent accounting firm reasonably acceptable to Secured Party.
 
     9.  NEGATIVE COVENANTS OF DEBTOR. Debtor shall not (a) create, incur,
assume or suffer to exist any mortgage, lien, pledge or other encumbrance or
attachment of any kind whatsoever upon, affecting or with respect to the
Equipment or this Agreement or any of Debtor's interests hereunder except for
those arising from or imposed by persons claiming by or through Secured Party or
Secured Party's assignees; (b) make any changes or alterations in or to the
Equipment except as necessary for compliance with clause (a) of para graph 8
above; (c) permit the name of any person, association or corporation other than
Secured Party to be placed on the Equipment as a designation that might be
interpreted as a claim of interest in the Equipment (provided, however, that
Debtor may place its name on the Equipment so long as such marking indicates
that the Equipment is subject to Secured Party's rights and interests as Secured
Party hereunder); (d) part with possession or control of or suffer or allow to
pass out of its possession or control any of the Equipment or change the
location of the Equipment or any part thereof except upon thirty (30) days
written notice to Secured Party from the location shown above, or on Schedule A
hereto; (e) assign or in any way dispose of all or any part of its rights or
obligations under this Agreement or enter into any lease of all or any part of
the Equipment except to (i) a wholly-owned subsidiary of Debtor or in connection
with the merger or consolidation of Debtor into a wholly-owned subsidiary of
Debtor, or (ii) an entity which acquires substantially all of Debtor's assets
and the successor entity agrees in writing to assume this Agreement; (f) change
its name or address from that set forth above unless it shall have given Secured
Party no less than thirty (30) days prior written notice thereof.

     10. EQUIPMENT PERSONALTY.  The Equipment is, and shall at all times be and
remain, personal property notwithstanding that the Equipment or any part thereof
may now be, or hereafter become, in any manner affixed or attached to, or
imbedded in, or permanently resting upon, real property or attached in any
manner to real property by cement, plaster, nails, bolts, screws or otherwise.
If requested by Secured Party with respect to any item of Equipment, Debtor will
use good faith efforts to obtain and deliver to Secured Party waivers of
interest or liens in recordable form, reasonably satisfactory to Secured Party,
from all persons claiming any interest in the real property on which such item
of Equipment is installed or located.
 
     11. EVENTS OF DEFAULT AND REMEDIES. If any one or more of the following
events ("Events of Default") shall occur:

         (a) Debtor shall fail to make any payment in respect of the Liabilities
within ten (10) days of the date when due; or

         (b) any certification, statement, representation, warranty or financial
report or statement heretofore or hereafter furnished by or on behalf of Debtor
or any guarantor of any or all of the Liabilities proves to have been false in
any material respect at the time as of which the facts therein set forth were
stated or certified or has omitted any material contingent or unliquidated
liability or claim against Debtor or any such guarantor; or

         (c) Debtor or any guarantor of any or all of the Liabilities shall fail
to perform or observe in any material respect any covenant, condition or
agreement to be performed or observed by it hereunder or under any guaranty
agreement which failure continues unremedied for more than thirty (30) days from
the date of notice of such failure from Secured Party; or

         (d) Debtor or any guarantor of any or all of the Liabilities shall be
in breach of or in default, which breach or default is not waived or cured
within any applicable grace or notice period in the payment and performance of
any obligation relating to any of the Other Liabilities; or

         (e) Debtor shall fail to comply, which failure is not waived, with the
financial covenants (as amended from time to time) set forth in its credit
agreement (as amended, restated or replaced, from time to time) with 
<PAGE>
 
Fleet National Bank, and its successors and assigns (collectively "Fleet Bank")
or in a credit agreement with any other financial institution which provides a
working capital facility secured by substantially all the assets of Debtor which
replaces the credit facility with Fleet Bank, in whole or in part (a "New
Lender"), and as a result of such failure Fleet Bank or such New Lender shall
declare an event of default under its credit facility with Debtor and shall
exercise its rights and remedies which are available upon such event of default;
or

     (f)   Debtor or any guarantor of any or all of the Liabilities shall cease
doing business as a going concern, make an assignment for the benefit of
creditors, admit in writing its inability to pay its debts as they become due,
file a petition commencing a voluntary case under any chapter of Title 11 of the
United States Code entitled "Bankruptcy" (the "Bankruptcy Code"), be adjudicated
an insolvent, file a petition seeking for itself any reorganization,
arrangement, composition, readjustment, liquidation, dissolution or similar
arrangement under any present or future statute, law, rule or regulation or file
an answer admitting the material allegations of a petition filed against it in
any such proceeding, consent to the filing of such a petition or acquiescence in
the appointment of a trustee, receiver or liquidator of it or of all or any part
of its assets or properties, or take any action looking to its dissolution or
liquidation; or

     (g)   an order for relief against Debtor or any guarantor of any or all
of the Liabilities shall have been entered under any chapter of the Bankruptcy
Code or a decree or order by a court having jurisdiction in the premises shall
have been entered approving as properly filed a petition seeking reorganization,
arrangement, readjustment, liquidation, dissolution or similar relief against
Debtor or any guarantor of any or all of the Liabilities under any present or
future statute, law, rule or regulation, or within sixty (60) days after the
appointment without Debtor's or such guarantor's consent or acquiescence of any
trustee, receiver or liquidator of it or such guarantor or of all or any part of
its or such guarantor's assets and properties, such appointment shall not be
vacated, or an order, judgment or decree shall be entered against Debtor or such
guarantor by a court of competent jurisdiction and shall continue in effect for
any period of twenty (20) consecutive days without a stay of execution, or any
execution or writ or process shall be issued under any action or proceeding
against Debtor whereby the Equipment or its use may be taken or restrained; or

     (h)   Debtor or any guarantor of any or all of the Liabilities shall suffer
an adverse material change in its financial condition as compared to such
condition as at the date hereof, and as a result of such change in condition
Secured Party reasonably deems itself or any of the Equipment to be insecure;

then and in any such event, Secured Party may, at the sole discretion of Secured
Party, without notice or demand and without limitation of any rights and
remedies of Secured Party under the Uniform Commercial Code, take any one or
more of the following steps:

     (1)   Declare all of the Time Balance to be due and payable, whereupon the
same shall forthwith mature and become due and payable as provided for in
paragraph 16 below, provided, however, upon the occurrence of any of the events
specified in subparagraphs (f) and (g) above, all sums as specified in this
clause (1) shall immediately be due and payable without notice to Debtor (the
date on which Secured Party declares all of the Time Balance to be due and
payable is hereinafter referred to as the "Declaration Date");

     (2)   proceed to protect and enforce its rights by suit in equity, action
at law or other appropriate proceedings, whether for the specific performance of
any agreement contained herein, or for an injunction against a violation of any
of the terms hereof, or in aid of the exercise of any other right, power or
remedy granted hereby or by law, equity or otherwise; and

     (3)   at any time and from time to time, with or without judicial process
and the aid or assistance of others, enter upon any premises wherein any of the
Equipment may be located and, without resistance or interference by Debtor, take
possession of the Equipment on any such premises, and require Debtor to assemble
and make available to Secured Party at the expense of Debtor any part or all of
the Equipment at any place or time designated by Secured Party; and remove any
part or all of the Equipment from any premises wherein the same may be located
for the purpose of effecting the sale or other disposition thereof; and sell,
resell, lease, assign and deliver, grant options for or otherwise dispose of any
or all of the Equipment
<PAGE>
 
in its then condition or following any commercially reasonable preparation or
processing, at public or private sale or proceedings, by one or more contracts,
in one or more parcels, at the same or different times, with or without having
the Equipment at the place of sale or other disposition, for cash and/or credit,
and upon any terms, at such place(s) and time(s) and to such persons, firms or
corporations as Secured Party shall deem best, all without demand for
performance or any notice or advertisement whatsoever, except that Debtor shall
be given five (5) business days' written notice of the place and time of any
public sale or of the time after which any private sale or other intended
disposition is to be made, which notice Debtor hereby agrees shall be deemed
reasonable notice thereof. If any of the Equipment is sold by Secured Party upon
credit or for future delivery, Secured Party shall not be liable for the failure
of the purchaser to pay for same and in such event Secured Party may resell such
Equipment. Secured Party may buy any part or all of the Equipment at any public
sale and if any part or all of the Equipment is of a type customarily sold in a
recognized market or which is the subject of widely distributed standard price
quotations Secured Party may buy at private sale and may make payment therefor
by application of all or a part of the Liabilities and of all or a part of any
Other Liabilities. Any personalty in or attached to the Equipment when
repossessed may be held by Secured Party without any liability arising with
respect thereto, and any and all claims in connection with such personalty shall
be deemed to have been waived unless notice of such claim is made by certified
or registered mail upon Secured Party within five (5) business days after
repossession.

Secured Party shall apply the cash proceeds from any sale or other disposition
of the Equipment first, to the reasonable expenses of re-taking, holding,
preparing for sale, selling, leasing and the like, and to reasonable attorneys'
fees and other expenses which are to be paid or reimbursed to Secured Party
pursuant hereto, and second, to all outstanding portions of the Liabilities and
to any Other Liabilities in such order as Secured Party may elect, and third,
any surplus to Debtor, subject to any duty of Secured Party imposed by law to
the holder of any subordinate security interest in the Equipment known to
Secured Party; provided however, that Debtor shall remain liable with respect to
unpaid portions of the Liabilities owing by it and will pay Secured Party on
demand any deficiency remaining with interest as provided for in paragraph 16
below.

     12. SECURED PARTY'S RIGHT TO PERFORM FOR DEBTOR. If Debtor fails to perform
or comply with any of its agreements contained herein Secured Party may perform
or comply with such agreement and the amount of any commercially reasonable
payments and expenses incurred by Secured Party in connection with such
performance or compliance, together with interest thereon at the rate provided
for in paragraph 16 below, shall be deemed a part of the Liabilities and shall
be payable by Debtor upon demand.

     13. FURTHER ASSURANCES. Debtor will cooperate with Secured Party for the
purpose of protecting the interests of Secured Party in the Equipment,
including, without limitation, the execution of all Uniform Commercial Code
financing statements reasonably requested by Secured Party. Secured Party and
any assignee of Secured Party are each authorized to the extent permitted by
applicable law to file one or more Uniform Commercial Code financing statements
disclosing any security interest in the Equipment without the signature of
Debtor or signed by Secured Party or any assignee of Secured Party as attorney-
in-fact for Debtor. Debtor will pay all costs of filing any financing,
continuation or termination statements with respect to this Agreement,
including, without limitation, any documentary stamp taxes relating thereto.
Debtor will do whatever may be reasonably necessary to have a statement of the
interest of Secured Party and of any assignee of Secured Party in the Equipment
noted on any certificate of title relating to the Equipment and will deposit
said certificate with Secured Party or such assignee. Debtor shall execute and
deliver to Secured Party, upon request, such other instruments and assurances as
Secured Party deems reasonably necessary or advisable for the implementation,
effectuation, confirmation or perfection of this Agreement and any rights of
Secured Party hereunder.

     14. NON-WAIVER; ETC. No course of dealing by Secured Party or Debtor or any
delay or omission on the part of Secured Party in exercising any rights
hereunder shall operate as a waiver of any rights of Secured Party. No waiver or
consent shall be binding upon Secured Party unless it is in writing and signed
by Secured Party. A waiver on any one occasion shall not be construed as a bar
to or a waiver of any right and/or remedy on any future occasion. To the extent
permitted by applicable law, Debtor hereby waives the benefit and advantage of,
and covenants not to assert against Secured Party, any valuation, inquisition,
stay,
<PAGE>
 
appraisement, extension or redemption laws now existing or which may hereafter
exist which, but for this provision, might be applicable to any sale or other
disposition made under the judgment, order or decree of any court or under the
powers of sale and other disposition conferred by this Agreement or otherwise.
Debtor hereby waives any right to a jury trial with respect to any matter
arising under or in connection with this Agreement.
 
     15. ENTIRE AGREEMENT; SEVERABILITY; ETC. This Agreement and the Schedules
and Riders hereto constitute the entire agreement between Secured Party and
Debtor relating to the Equipment and supersede all prior and contemporaneous
conversations, agreements and representations relating to this Agreement or to
the Equipment. If any provision hereof or any remedy herein provided for shall
be invalid under any applicable law, such provision or remedy shall be
inapplicable and deemed omitted, but the remaining provisions and remedies
hereunder shall be given effect in accordance with the intent hereof. Neither
this Agreement nor any term hereof may be changed, discharged, terminated or
waived except in an instrument in writing signed by the party against which
enforcement of the change, discharge, termination or waiver is sought. This
Agreement shall in all respects be governed by and construed in accordance with
the internal laws of the State of New York, including all matters of
construction, validity and performance, and shall be deemed a purchase money
security agreement within the meaning of the Uniform Commercial Code. The
captions in this Agreement are for convenience of reference only and shall not
define or limit any of the terms or provisions hereof. This Agreement shall
inure to the benefit of and be binding upon Secured Party and Debtor and their
respective successors and assigns, subject, however, to the limitations set
forth in this Agreement with respect to Debtor's assignment hereof. No right or
remedy referred to in this Agreement is intended to be exclusive but each shall
be cumulative and in addition to any other right or remedy referred to in this
Agreement or otherwise available to Secured Party at law or in equity, and shall
be in addition to the provisions contained in any instrument referred to herein
and any instrument supplemental hereto. Debtor shall be liable for all costs and
expenses, including attorneys' fees and disbursements, incurred by reason of the
occurrence of any Event of Default or the exercise of Secured Party's remedies
with respect thereto. Time is of the essence with respect to this Agreement and
all of its provision.
 
     16. REPAYMENT; REBATE; INTEREST. Except for the installment payments of the
Time Balance as set forth in the Schedule of Obligations, the Debtor may not
prepay the Time Balance, in whole or in part, at any time. In the event Secured
Party declares all of the Time Balance to be due and payable pursuant to clause
(1) of paragraph 11 above, Debtor shall pay to Secured Party an amount equal to
the sum of (a) all accrued and unpaid amounts as of the Declaration Date plus
interest thereon, and (b) the present value of all future installments set forth
in this Agreement over the remaining unexpired term of this Agreement discounted
to present value using a discount rate of five percent (5%), provided that the
amount of interest earned by Secured Party computed as aforesaid shall not
exceed the highest amount permitted by applicable law. The Time Balance as
reduced to present value in accordance with the preceding sentence shall bear
interest from and after the Declaration Date, and all other Liabilities due and
payable under this Agreement (including past due installments) shall bear
interest from and after their respective due dates, at the lesser of 14% per
annum or the highest rate permitted by applicable law, provided, however, that
Debtor shall have no obligation to pay any interest on interest except to the
extent permitted by applicable law.
 
     17. CONSENT TO JURISDICTION.  Debtor hereby irrevocably consents to the
jurisdiction of the courts of the State of New York and  of any federal court
located in such state in connection with any action or proceeding arising out of
or relating to this Agreement with an additional copy sent in the same manner to
the same address, marked to the attention of Debtor's general counsel and
service so made shall be complete five (5) business days after the same shall
have been posted as aforesaid or the transactions contemplated hereby.  Any such
action or proceeding will be maintained in the United States District Court for
the Southern District of New York or in any court of the State of New York
located in the County of New York and Debtor waives any objections based upon
venue or forum non conveniens in connection with any such action or proceeding.
Debtor consents that process in any such action or proceeding may be served upon
it by registered mail directed to Debtor at its address set forth at the head of
this Agreement or in any other manner permitted by applicable law or rules of
court.  Debtor hereby irrevocably appoints Secretary of State of the State of
New York as its agent to receive service of process in any such action or
proceeding.  Debtor and Secured Party 
<PAGE>
 
hereby waive any right to a jury trial with respect to any matter arising under
or in connection with this Agreement or the Equipment.
 
     18. NOTICES.  Notice hereunder shall be deemed given if served personally
or by certified or registered mail, return receipt requested, to Secured Party
and Debtor at their respective addresses set forth at the head of this
Agreement. Any party hereto may from to time by written notice to the other
change the address to which notices are to be sent to such party. A copy of any
notice sent by Debtor to Secured Party shall be concurrently sent by Debtor to
any assignee of Secured Party of which Debtor has notice.

     19. QUIET ENJOYMENT.  So long as no Event of Default has occurred and is
continuing under this Agreement, Debtor shall be entitled to peaceful and quiet
use and enjoyment of the Equipment during the Term and such peaceful and quiet
use and enjoyment shall not be disturbed by Secured Party, Secured Party's
assignees or any person claiming by or through Secured Party.

     20. EARLY TERMINATION.  Provided that no Event of Default has occurred and
is continuing under this Agreement, Debtor shall be entitled, at its option,
upon at least thirty (30) days prior to written notice to Secured Party
specifying the termination date, to terminate any Agreement prior to the
expiration of the Term thereof by paying to Secured Party an amount equal to the
present value of the remaining rent payments as of the termination date
discounted at the rate of five percent (5%) for all of the Equipment subject to
such Agreement together with any accrued and unpaid installment payments as f
the termination date.

     The Debtor agrees to all the provisions set forth above.  This Agreement is
executed pursuant to due authorization.  DEBTOR ACKNOWLEDGES RECEIPT OF A SIGNED
TRUE COPY OF THIS AGREEMENT.

Date:September 28, 1998

PSINET INC.                          CHARTER FINANCIAL INC.