Now for something practical. I run AVG free version myself and uninstalled Norton and Mcaffee at least a year ago. I also run only Firefox rather than IE, I won't touch IE with a bargepole and a health inspector on the end.
Read this article for a really good expose on this whole issue.
After reading this I think I will upgrade to the paid AVG version, well worth the money methinks.
http://justanothercoverup.com/?p=608