How does one block Internet access to a computer on a network?

The computer has to be able to use the network, but not have access to the Internet. The server environment is Windows 2000 server SP4, the computer could be running either Win 2000 or WinXP Pro. Most systems run with a dynamic IP address with specific machines set with a static IP for the particular job they are used for. Internet connection goes through a firewall appliance and then on to a router.

How does one block Internet access to a computer on a network?
well if you are using a hard ware manged fire wall just block that pcs mac address in the fire wall and cut out all internet ports so it can not go out. easy way.
Reply:access your firewall and block outgoing Internet requests for the particular PC you want to deny access.