Having been hit by some SpyWare recently I did some research, and NOT Porn related, oddly enough..
Now I use Spybot Search & Destroy www.spybot.info to detect and remove Spyware and AVG - www.grisoft.com for Anti-Virus..
I tried Adaware, Pest Control, etc... and SpyBot found and removed more stuff than all of them put together.
I'd also recommend CWShredder (only useful if you've been hit by CoolWeb), and HiJackThis - which is a general purpose malware detection/removal tool (it scans registry for dodgy entries)....
(mind you if I had a PC with only that stuff on it I'd be V. tempted to format and start again!)
Good luck