I find that having a healthy mix of AVG, SpySweeper and maybe SpyBot S&D (for the really pesky spyware) goes a long way towards keeping your computer free and clear of problems.

Of course, I also go into the registry to manually remove files, but then again I'm a professional.

Also, you might want to think about what sites you're visiting. How is the Spyware/Malware/Virii getting onto your computer? Do you search for BitTorrent sites, or visit keygen/hax0r sites? take a screenshot of your processes, and after a few weeks, go back and see how many you have. If there's malware or spyware or alot more processes, and you haven't voluntarily installed anything during that time...well, the problem is most likely a site or two that you visit frequently.

Just a suggestion, though.