I caught the Vundo years ago. It was very difficult to get rid of back then. Hopefully it's easier now.
If you know what file is infected, you might be able to kill the vundo process via the task manager and then delete the file.
Another good tool is the CCleaner you can download from CNET. Using that program makes it easy to kill/remove files and virus that are kicked off at boot time. In CCleaner, Goto "Tools" and "Startup" to remove things from startup that you don't want. The easiest suggestion I have though is to download a 30 day free trail version of Norton, let him find it and fix it. As much as I've hated Norton over the years, he has gotten better and the trail version may fix you up. I didn't have much luck with AVG on my system.