Im guessing by re-intalling windows you have a 2000/XP cd? If you do and your planning to use it for the install you can format it as part of the process.
Otherwise try a program like FDISK from microsoft (on windows CD or download). There are plenty of freeware programs out there that are simular and all will remove the partition tables and reformat.
Unless your wanting to 100% wipe all i wouldnt bother with a low level format, standard one is more than sufficent.
Philbert
August 2007