You can try the Starter Edition of Spydoctor, it's part of the Google Pack.
I run spyware and adware scans every week using SpyBot and Ad-Aware, but Spydoctor managed to find a lot of things that the others didn't find.
Go to this webpage and uncheck everything except for Spydoctor:
http://pack.google.com/intl/en/pack_...FRAkggodF3nG2A