When you say see the rest of the network, I suppose you refer to looking at each other's shared folders?!
1) Filter out NET-BIOS if your router permits.
2) Those who doesn't want praying eyes on...

I just come to thinm, if you are using apache/php and have module rewrite active, then you could possibly use a rewrite rule. I am not really very good at writing rewrite rules, so please ask someone...