I use the following:
Ad-Aware SE Personal
Adware Away
Spybot - Search & Destroy
Spy Bouncer
Spyware Blaster
Spy Audit
Hi-Jack This
and thats only 'Spyware' programs were talking about. 'Google' them if you want them.
Up-Date them as often as possible as new treats emerge everyday and use them regularly.
They all have there own specialities and detection databases.
I use to think I'll have one 'Anti-Virus', one 'Ad-Ware Detector', one 'Registry Mechanic' and so on to keep things simple but it don't work like that. It's BULLOCKS.