firewall gateway server using ubuntu server

[lianlian]

I want to set up my ubuntu server 5.10 to be the gateway for all of my computers at home. the ubuntu server will be behind my dlink router, so the ubuntu server's gateway is the dlink router. i'll have peerguardian running on the server to fitler traffic for all of my computers. so, anything that is blocked by peerguardian on the ubuntu server will be blocked for the other computers. basicly i want to have a center point firewall server.

so can anyone point me the direction, please. thankyou.