Restrict internet access on specific networked clients.

Please help me. I would like to resitrict internet access on specific networked clients.

I have two servers both running Win Server 2003 Standard Edition.

1 server is a File and Print server, and the other is the internet Gateway of all my clients.

I have 28 clients, but i only want 5 clients to have unlimited internet access and block the rest. At the same time the ones that i want to block i still want them to be able to do Antivirus updates..

All your responses are greatly appriciated…………..