Internet diabling

i have a network whereby i have internet connection sharing enabled on the windows 2000 server and also has dhcp. so the computers pik up ip address automatically. i want to diable internet and chating on certain pcs this pcs share and also print using tcp/ip soo is there a way to stop the internet only and allow to browse the Network Neighborhood and see the computers. and i also wnt the norton antivirus to have its update done automaticaly. is that possble kindly any1 help and hope there is no need to buy any new software. thanks