I hope I never have the chance to describe my own adventure like this: ComputerZen.com - Scott Hanselman - Tracking down a Trojan

As of late, I've been using the tools more for tracking down why more computer is slow and who is dorking around scanning the disk.

This, too, could be an example of a trojan. My only hint that a fresh-installed Win2K machine was infected was when I looked at the upload / download rate (I was downloading the security patches) and mused: damn, sure is uploading a bunch more than it should... hmm... oh, no!

That's been my only compromise. And I keep looking.