Much as this will likely take a while if you have over a terabyte of storage, if you use "Derek's Boot and Nuke" and burn it onto a CD, pop that bad boy into your optical drive, then boot from the CD, it will completely wipe all drives by erasing, writing, erasing, writing, erasing, writing, erasing. Nothing left whatsoever. Much as this will ditch all files you used to have on your Windows 7 setup, if you use the Windows CD and boot from it again, you will at least be able to use your computer again. Worked for me when a school desktop got heavy viruses.