The worst virus I’ve ever seen is now making its way through Bit Torrent and Limewire and other file sharing programs. It’s called Virut. And once you have it it’s pretty much game over and time for a clean install. You’re done. At least you’re operating system is kaput. So if I were you I’d make sure your anti-virus is working and updating regularly. And stay away from P2Ps until this settles down. Lots of people are losing everything on their computers. What makes Virut so nasty is that it patches itself to every executable, so everything time you run an anti-virus, it “patches itself” onto the anti-virus. Also it changes system files, so if you “delete” instead of “cure” or “heal” them, you’ll be facing at least a Repair install.
Some fixes for Virut run in Safe Mode, but on my client’s computer, Safe Mode isn’t working. I’m right now trying a method I saw on the Internet that uses Dr. Web. Cure-it.