I am sure most people running *nix are familiar with rootkit detectors, but now that rootkits are targeting Windows boxes, and current antivirus and trojan hunters don't detect them there, a few new rk checkers for Windows are coming out.
F-Secure has one in beta, free until July 1, 2005 called Blacklight. It's fast and effective.
Microsoft has one as well, called Ghostbuster, that comes in 3 flavors.
Sysinternals version is called RootkitRevealer and is now very capable, after changing the way it's called to run. It uses a randomly named copy of itself, to thwart the attempts at targeting it.

Check them out, see what works for you, and add one to your arsenal. The best offense is a good defense.

I did a search but didn't see anything on this, so just wanted to bring it out. The May 10th issue of PCmag has an article on Windows Rootkits if anyone has it.