I have found spybot to be one of the best spyware/adware removers around...its free and you can offer a link to it to your surfers so they can clean up their machines for no cost and then you also seem like a really nice guy so maybe (just maybe) they will bookmark your site and come back and make you some money!
Anyhoo....the link is
http://www.spybot.info/ (don't go to the .com/.net versions as those ones apparantly try to install spyware themselves!)
cheers,
Luke