I wouldn’t muck about with it, download any linux distro, boot into linux, remove any precious data onto a USB stick / External hard drive. Format hard disk and reinstall windows.
Will probably be quicker in the long run.
EDIT:
Download this on a spare machine:
Linux DVD
or this if you haven’t got a DVD writer:
Linux CD
Burn it, then insert into the infected machine and reboot the infected machine. All being well it will boot straight into Linux, and will allow you to click and point your way around the old system to save anything you want to keep to an external drive.
If the screen doesn’t go green and look slightly different, you may have to change the ‘boot options’. When the computer starts, it’ll say ‘press F1’ or ‘F9’ to either ‘enter’ or ‘change settings’. Just look for the bit that makes the CDROM the first option.
HTH.