The PC Essentials
SuperAntiSpyware is an excellent and free way to get rid of and protect your computer from malware, spyware, trojan, and other crap.
Spybot Search and Destroy is clunky and sometimes freezes up, but it's free and has found things that SuperAntiSpyware couldn't detect.
CCleaner wipes out all the temp folders and other junk. It also has a good registry cleanup tool.
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