I Believe what you mean is Format. If this isso, the you will need a Win98 Bootdiks, which you can download from
here. Boot the PC with this in the drive, and when you get to the A:>\ prompt, type in format c:\. this will erse everything on the drive. So backup everything you wan't t keep. Ohh and have the drivers for every piece of hardware in the PC, handy after you reinstall windows.
Hope it helps