Don't listen to the Adware or Spybot suggestions. The best product out there by far is Microsoft's Antispyware. This stuff ROCKS.
http://www.microsoft.com/athome/security/spyware/software/default.mspx
absolutely agree...the new anti-spyware program by Microsoft is awesome!
It is really good, isn't it? Since you recommended it before, I haven't had one!
My recommendation is to use all three... Ad-Aware, Spybot Search and Destroy, AND Microsoft Anti-Spyware. I have cleaned PCs that required all three to get everything. AND even then, on one, infected with Cool Web Search, I had to use a fourth program... CWShredder.
After downloading Spybot AND GETTING THE LATEST UPDATES... Boot into SAFE MODE and run Spybot in Safe Mode. Then run Ad-aware. Boot back into regular Windows and runs Microsoft Anti-spyware to finish... it's surprising how many pieces are left behind by the other two. But if you do it the other way, the other two will find pieces left behind by MS Anti-Spyware. You may have to run CWShredder if "Cool Web Search" keeps popping up. That one hides re-installers everywhere.
Its a good idea to run them twice... or even three times.
Yes... Microsoft's will find things that other have not.