if its your primary hard drive that you want to format you can use your OS set-up disc to format and re-install windows.
if you want to format a secondary hard drive that has no OS on it you can just find it in "my computer" and "right click" and "format"
............................................................................................Main System Spec: Intel Quad Q9550 (OC to 3.4Ghz), Gigabyte Ga-ep45-ud3l, 4gb kingston hyperX @ 1066mhz, Corsair tx 650, Nvidia 8600GT.