mikesgroovin-
knowing how TCP/IP works and the other internet protocols wont help. Cause how we comminicate over the net is very broad and different. Forums, IM, IRC, BitTorrent, Skype, HTTP downloads...all of them use different means. But all have one thing in common. Packet transfers. SO honestly how does knowing internet communication gonna do anything?
As for the original poster-
What Server OS are you using? Server 2003? Server 2008? Windows Home Server? I know Avast has got a AV for WHS they are working on now. But Server AV and Firewalls should be different and more secure than your PErsonal.
Symantec Corporate should be your Anti-Virus for the Server. Perhaps NOD32 could be used as well. You want something that has a very high detection rate. Firewall you want something super secure to prevent hacking and also easy to configure so that you can allow PC's to access it and use it like they should.