You could try
Hijack This! if you're having problems w/ spyware (I like it a lot, but I'm a pretty technical person, and so is HT!).
SpywareBlaster is good a preventing malware infections as well.
Also, try MS's tools (I don't have links for those, but I hear they work well).
Last resort: switch to Linux. It isn't that difficult anymore, if you aren't running server processes (no harder than Windows, anyway).