I would suggest what others have, Avast or AVG. Too many people buy Norton of Mcafee and those are the most commonly exploited due to their popularity. One of the biggest things I can suggest is to use another browser other than Internet Explorer (also exploited the most...Firefox is good, Chrome is better in my opinion), stay away from sketchy sites, and never download things from sites you aren't familiar with. With Chrome and Firefox, you can install Ad-Block which will prevent ads from displaying on your page too. They slow your browser, and some times can be malicious.

One problem you may run in to if you already had some form of virus protection is that is difficult to remove. They install things in the registry of windows, and only a registry cleaner (c-cleaner or something like that) will actually remove it. When you install some other form of virus protection, it will think the leftovers are a virus.

What ever you use, make sure that it is updating often as well. Some people will install good virus software, and will never let it update. Virus software is only as good as the updates it puts out to prevent new viruses. One thing is for sure, paying more isn't always better when it comes to virus software, you would be surprised at how well the free stuff works.

I ramble on for hours, but to answer your question, I would go with Avast or AVG.