Check out http://www.eset.com/ for NOD32. I think it is amazing.
It's not free, but it's not Norton. Although Norton has it's good points, the problem is that when it's running, it's an absolute resource hog. It completely bogs down your computer when a scan is running, updates take over your system, and even your boot speed is affected. And Norton doesn't protect against everything.
NOD32 is cheaper than Norton and McAffee. Once installed, the monitoring console will run in the background. When it needs an update, it gets one and tells you that it now has the latest version. When something malicious tries to intrude into your system, it stops it and notifies you immediately. It runs on very low resources so you will not see system performance degrade. I've been using it for about a year and a bit now, with no firewall protection, and I haven't had any viruses or anything mailicious on my system since. Definitely worth a look.
If you want some more info from me, contact me through either ICQ or MSN (firstname.lastname@example.org)
i can't agree more, it is the best, plus it tackles adware, spyware, and every other piece of malicous software out there, not to mention it updates daily so you are always up to date, even on christmas!