I did not know of a reliable anti-virus application for Windows until recently. I have been recommending paying for one of the standard programs, and I think that might change with my discovery of AVG's free version.

AVG Anti-Virus Free Edition was featured in Patrick Norton's favorite free software segment on The Screen Savers. I don't have a whole lot of experience with the program yet, but since I have less than two months left on my Norton subscription, I'll be transitioning to AGV and will keep you updated.

I use almost all of the free software Patrick recommended in that article. I know nothing about Winamp, but I second him on all the rest. I even like them better than the Microsoft equivalents.