I have used Symantec Anti-Virus and it just bogs down my Windows XP system and is very annoying. I have heard that AVG and Computer Associates are much better.

I have used for about 3 years and highly recommend Computer Associates Anti-Virus product ( http://wize.com/utilities/computer-associates-a... ).

It's very low-impact on the system. By this I mean I have not noticed a big slowdown when it is doing its realtime scan. The price is also well within most budgets and they come out with frequent updates.

If you don't go with CA, the only one I definitely DO NOT RECOMMEND is Symantec. Symantec products are notorious for slowing your system to a crawl and being impossible to every uninstall!