Home network

Hy!

I have a question:

we have a small network of 8 computers with our neighbour, over a simple switch.
al pc run winxp sp2.
1 pc has internet connection(cable modem)

the question is. how can we share this conection for only 2 addition pc, so, that those 3 pc to have full acces, and the other 5 to not have ANY acces to the net. Per moment we are using kerio winroute firewall, this solves a part of the problem, so we can navigate over the http protocol, but we can’t use ANY other things, like P2P, Hubdownload(DC++), or even SHTTP acces….

Please, we accept any ideas…