David
-Spybot Search & Destroy
-Lavasoft Adaware, free version. Run this and spybot whenever you feel like it, once a week/month whatever
- getfirefox.com if you haven't already, and...
Also Cleanup XP from
http://stevengould.org/downloads/cleanup/CleanUp452.exe. Will delete 600mb of junk files on a fresh install of windows. Just make sure you untick cookies, it's a pain in the ass to have to log back into every forum etc.
Don't worry about a firewall with these apps and common sense.