AVG is good but I recommend (free for non-commercial use) for my customers. I don't recommend add on software firewalls such as Zone Alarm. For most people they usually cause more headaches than they prevent.
If you got Comcast, or for that matter if anyone has Comcast Internet you get McAfee for free and it KILLS Norton. Its a great anti-virus. Free download, and blah blah if you got Comcast. But wait did I hear right.. you buy programs? eeek. I've never had that feeling of buying programs before.
I like even though it is not free because of its lightweight usage of system resources. On one comp though I'm trying out the Panda 2009 which is free for 90 days. My own opinion on AVs would be as follows :-
Free :
1. AVG
2. Avast
Non-Free :
1. Eset Nod32
2. ZoneAlarm
YMMV but the ignoramus approach like theGOOCH (no-AV) is laughable, even my granny uses an AV.