Very well put IKnowNot...

This is what I use @ home:

4 PC's (XP) and 6 VM's (2000,98,SuSE8,Novell6,Solaris9x86,&XP)
CableModem to NAT (My router has the option to log to a couple of software firewalls) to SonicWall to ZAP (ZoneAlarmPro) but only on one PC is ZAP because I have dedicated this PC to be my "Internet" PC but all the other PC's have NAV therefore I am not worried about WAN traffic compromising my nitwit

My SonicWall 75 is probably a bit of overkill but configuration is always the key in a home LAN environment...there's my 2 cents

Have fun