you're not going to get that easy of a response without a bit of reading. First, check out the following resources:
http://www.samba.org - Samba is an SMB server suite (the same type of networking used in Windows) for Linux/Unix OSes. It allows you to integrate Linux into your existing Windows network, and if done right, actually replace your servers.
http://www.squid-cache.org - You should really go through the FAQ for squid. No one should be insane enough to try to answer your question.
linux server
