My ISP recommends ALL of the following. I downloaded them all. I've been running Spybot, but got the newer version and it found some stuff. Then I downloaded, installed and ran Ad-Aware, and it found a bunch more stuff. I got CWShredder, and it didn't find anything further. I am EXTREMELY careful about stuff like this, but there isn't much you can do to prevent getting spyware/adware on your system if you don't have programs to protect you.
Ad-Aware: Gets some things that Spybot S&D doesn't.
CWShredder: A small utility for removing CoolWebSearch (aka CoolWwwSearch, YouFindAll, White-Pages.ws and a dozen other names). Spybot S&D and Ad-aware may not get everything.