[Bungleau]

I concur with TDC. Haven't tried the MS version, so I've no opinion there.

TrendMicro also offers an on-line spyware/malware scan. It picks up some things that Spybot and AdAware don't, so it's worth it as a final line of defense.

And if you're more technical and savvy, look at HiJack This. Rather than looking for bad programs, it looks for bad behaviors and lets you decide what to do with them. It can be very, very helpful. And very, very tedious, too, if you don't have good access to Google when you review the logs.