Just wanted to post a heads-up. There is a conflict between Microsoft's update KB951748 and ZoneAlarm. Something about that update will cause ZoneAlarm to block your browsers from internet access and ultimately shut your connection down. ZoneAlarm is recommending that you uninstall this update as a fix for right now. Turning your ZoneAlarm setting down to "medium" will also fix this problem, but obviously will reduce the level of security provided by the program.
If you're going with AVG, I totally reccomend paying the $40 for a 2 year Pro license. I found it is better than the free version, especially with email scanning. Anyone who puts NAV on their PC deserves everything they get. :)