Updated to show current versions of recommended applications:
HijackThis - see previous post (#20)
Spybot S&D 1.3,
http://safer-networking.org/en/download/index.html
Ad-Aware 1.05 SE,
http://www.lavasoftusa.com/
CWShredder 2.12,
http://cwshredder.net/bin/CWShredder.exe
Update and run your existing antivirus, then follow up with Housecall (
http://housecall.trendmicro.com/hous...start_corp.asp) and Panda Active Scan (
http://www.pandasoftware.com/actives..._principal.htm) to be totally thorough. IE required as they both require ActiveX.