I prefer Zone Alarm Pro. It is just a solid firewall app. Norton 360 is a lot of apps (firewall, antivirus, antispam, etc.) rolled into one but it creates a lot of overhead on the PC and seems to slow it down a lot because of all the things it is running.

I use ZAPro for the firewall, and Norton/Symantec's antivirus software. You might be able to use just the AV after installing by turning off the other features.