Windows Defender: Microsoft's Answer to Spyware
Windows defender is a free tool to detect and delete spyware. It was written by Microsoft to answer the spyware problem that users of Windows have to face. However, it works only on Windows Xp SP2. If you have a Windows Xp version that is older, consider updating it to SP2. And if you have Windows 2000 or 98 or older, a third party anti-spyware solution is the only option left to you. Windows Defender comes by default with Windows Vista and Windows Live OneCare.
Windows Defender Screenshot

Recommended Spyware Removal Tools:
Spybot-Search & Destroy
Spybot - Search & Destroy is a free anti-spyware solution that is very effective in detecting and removing...More information
Spyware Terminator
Spyware Terminator is a free spyware removal tool that is highly effective in protecting your computer...More information
SpywareBlaster
SpywareBlaster is a free spyware removal tool from a small company called Javacool software. However,...More information
Other Tools:
Hijackthis
HijackThis is a free tool which scans your computer to find settings that may have been changed by spyware, malware or other unwanted programs...More information
CCleaner
CCleaner is a freeware system optimization, privacy and cleaning tool. It removes unused files from your system - allowing Windows to run faster and freeing up valuable hard disk space...More information