right m8 boot up of your startup disk and follow theese instuctions

1)type "a:\" (without the speech marks) and press enter
2) type "fdisk" (without the speech marks) and press enter
3) press "y" to enable large disk support (if it asks you)
4) look through the lists that come up until you find your partition and delete it.
5) restart the system with bootup disk still in
6) format your hdd
7) reinstall windows

if you need anymore help post back m8 hope this helps Dave