SpywareBlaster

Unlike other programs, SpywareBlaster doesn't scan for and clean spyware. Instead, SpywareBlaster provides protection against spyware ever installing and can also prevent spyware from running if it is already installed on your machine! SpywareBlaster can also protect against spyware/tracking cookies (this cookie protection function requires Internet Explorer 6 or above - the spyware protection mechanism even works on Windows machines without Internet Explorer). SpywareBlaster is a freeware.

Spybot - Search & Destroy

Spybot - Search & Destroy can detect and remove spyware of different kinds from your computer. Spybot-S&D can also clean usage tracks. Spybot-S&D is free, so there's no harm in trying to see if something snooped into your computer, too :)

Ad-Aware

Ad-Aware SE is the latest version of our award winning and industry leading line of antispyware solutions and represents the next generation in Spyware detection and removal. It is quite simply the most advanced solution available to protect your privacy. With the all new Code Sequence Identification (CSI) technology that we have developed, you will not only be protected from know content, but will also have advanced protection against many of their unknown variants.Designed for Windows 98, 98SE, Win ME, Win NT 4, Win 2000, and Win XP Home/Professional you can be sure that you will have the most effective privacy protection that has ever been offered by Lavasoft. Ad-Aware SE Personal edition will comprehensively scan your memory, registry, hard, removable and optical drives for known Data-mining, aggressive advertising, Parasites, Scumware, selected Keyloggers, selected traditional Trojans, Dialers, Malware, Browser hijackers, and tracking components.