RootkitRevealer

RootkitRevealer is another great tool from SysInternals. While this tool has been out for a while, with the latest launch of Sony/BMG’s evil stealth rootkit from their music cds, the rest of the world is now privy to the world of rootkits.
This is purely for a Windows system and consists of the types that come from spyware and adware mainly but there are other exploitable kits out there specifically for Windows. This gives you the detailed look at seeing if you’ve been compromised.
Via SysInternals