Spyware is what you can get by surfing the Internet even if you had the software above. Ever wondered why the starting page of your browser is "http://www.adcentergaypornhappierlifesearchengine.com" and even if you change it, it comes right back? Or suddenly out of nowhere opens up an browser window telling you've won a national lottery? You just can't think how happy you are, I mean, what are the changes to win in a lottery! Yeah right, but if you're annoyed by all this try these tips and tricks.
Ad-Aware, Lavasoft, free for non-commercial use
No usage experience, but the name popped right on my mind.
Spybot - Search & Destroy, http://beam.to/spybotsd, donationware
No usage experience, but the software seems good. Free and available in most languages. Great work boys!