Make a bootable Usb flash Drive that will be used to format computer instead of a disk with the use of WinToFlash. one of the main advantage of using flash drive to format your system is that is it faster than ordinary disk
Things needed for this tutorial:
-USB Flash disk/Flash drive/Pen drive/Thumb drive, etc
-A copy of Windows XP/Vista/7/8 setup files in a folder( you can get this by copying it from the disk)
-Computer
A complete guild on How to create this with a graphical illustration is located at http://www.baricblog.com/2013/01/how-to-install-windows-xpvista78-from.html