Alright I just wanted to post a few suggestions for this, which I like to use.
Norton Antivirus, is always a good choice for virus protection. They have a live updater that will automatically keep your program up to speed on virus definitions. I am not too sure on some of the other ones but maybe someone can elaborate.
What I am sure about is Zone Alarm. I really love this program. It is a firewall, pop up blocker, email protection and everything all in one. The main thing I use it for is a firewall.
Whenever you go into a program, it lets you know that program is attempting to access the internet, and asks you for permission if it's alright. You answer yes or no, and can even check a box saying to remember that program for now on of that answer. But alot of hackers try to ping you for ip addresses and the such, and this blocks all your ports and protects them. Whether it be from ad pings, or hackers.
Very good tool to have. I have just put in a intel i865 pearlx motherboard onmy pc and took outy my old jetway and unfortunately I had to partition my hard drive for a clean install of windows, so I lost my old count of protection stats. But since I got it back u and running about 3 weeks ago, I have had 335 intrusins blocks and nine of them have been high rated.
One other tip for protection, get a program called Ad-Aware. Try going to downloads.com ,I think they have a free 30 day share-ware version, or it might even be free now, but it will scan your pc for ad bugs like "double-click' "cydoor" and etc. If you have kazaa remember that when you run ad-aware kazaa will not work unless you have the required ad programs that are preinstalled on your pc. But if you have kazaa-lite, no fret there.