I would assume that the virus would have infected your windows files, wich virus scans would be pointless. Once certain files are infected and deleted or quarintened by the virus software they are gone, and once certain windows files are gone it will no longer function properly.
System restore maybe. But if you dl'd and installed some p2p filesharing crap, more than likely its intended purpose is to set restore point with the virus, than do its magic, making your restore infected. I saw a "hacked" version of norton wipe out a bios on a guy last year, killing the mobo. He said " I clicked the setup file and my computer froze" it was toast. never would even post again.
Remember anyone can upload stuff on those sites, including the computer programmers that are loosing money because of the software being pirated (thePIRATEbay).
Your best bet is to load up files you need onto usb drives, and reformat.
once windows is reinstalled, get your virus protection up to date, then scan the usb sticks BEFORE you tranfer them back to your HD.
Say NO to ilegal p2p and bittorrent. SPECIALLY .exe files
try using peer gaurdian if you have legit bttorrent sites you use, I do alot of live music trading, which is legal, but still use a program to block ports and ip addy's.....