i know that, idont back anything up though, too complicated. i just delete everything and start from scratch but i always end up writing over the previous partition. i might use kages manual to reformatte my computer soon.
If you have more than one partition though, you will have to do the same thing for all of them , since you'll have C:\ D:\ etc. If you wanted to wipe a partition, you'd have to do this using the Windows installer