Security updates are great and all but the fact that the hackers figure out how to bypass them mere hours after they're released doesn't help worth a damn.
For your current problem do a Google for Adaware and get it (1.07SE I think) and Spybot Search & Destroy and get it too. Run one after the other (after updating) they're a pretty good combination.
Out of the totally free spyware scanners the two I mentioned are the only ones worth messing with. Yes you can get trials of the pay spyware scanners but do your homework. Most of them (sadly) infect your PC with malware when you do the free scan then want you to pay for the full version to disinfect your PC that it infected in the first place.
I have always used Adaware/Spybot/Defender and The Cleaner, personally. The cleaner is a trial, but it lasts 30 days. Usually I only needed to use it once per install anyway.