Secured Net Sharing .. Help Needed

There is one Dell Server with 2 NICs.
One Nortel Secured Router and Nortel Switches.
All I need is
1.) Server Operating System Shud be SuSE
2.) Squid to be configured on that dell server

All clients can access net only via proxy
no porn sites
no adult contents
and I even want to add some more websites that are to be restricted.

how do i proceed?
I wud be really grateful if anyone has enough patience to provide detailed information about various configurations needed…

Some routers have keyword blocking configuration.