http://www.lavasoftusa.com/software/adaware/ ---> Ad-aware is, in my opinion, the best thing to clean the stuff in your computer. It’s a must have if you happen to have Kazza
http://www.safer-networking.org/en/index.html ---> very useful little device that cleans the things Ad-aware can't clean.
http://www.download.com/3000-2092-10039884.html ---> Trust me on this one: you want Zone alarm. Cleans spy were, damn good firewall, controls mail, stops pop-ups... all you need, I tell you!
http://www.zonelabs.com/store/content/promotions/spywarescanner/scanner.jsp ---> free on-line spy were scanner. The scanner is an ActiveX application that is currently supported on Internet Explorer v5.01 or higher. Other browsers such as Opera, Netscape, or Mozilla do not support ActiveX applications at this time.
http://www.pandasoftware.com/ ---> Panda software: go to the left bottom corner of the page and it will tell you if your PC is infected or not (with some luck, most of the stuff gets cleaned as well)
http://www.trendmicro.com/en/home/us/personal.htm ---> ‘Nother virus scanlator, online.