Windows NT – clients access (Urgent)

Hi there,
I have two NT servers : A & B
On my NT server-A there are 70 users accessing Accounts and other applications
On my NT server-B(Proxy Server)there are 500 users accessing the server to access the internet.

I have one WIN95 client-PC which needs to access both the Servers A & B. But none of my users in server B should be able to access the Server A and any of its resources.
I also have a cisco 2610 router.How can I setup the network so that Users in both Server A & B can access the internet thru router ,but B users should not access-A execpt for One Win95 client