If you are not a Mac user, and I sincerely hope you are not, I have found three programs to be quite profound in the daily plight against spam, registry problems, and general pc care. If you are a mac user, and you are smugly thinking that you don’t have these kinds of problems, that’s because – oh never mind.
http://www.pcregistrycleaner.com/ This cleans up the registry. Incredible boost in performance after using. They have a free version, but you will end up paying $39 for full version. It’s worth it.
http://www.iolo.com/sm/7/ This is a general pc maintenance and care program. Excellent. Let’s you do a massive amount of things. I use this daily for tuning up.
http://www.enigmasoftware.com/ This is a great spyware hunting program. I know there are some other free ones, but this is industrial strength.