Computer Wiping Questions

Awhile back a friend of mine thought it would be funny to wipe my computer. Well he's passed out at my house right now and his laptop is in his car. I have his keys so I can get it. How do I wipe it? I have no XP disk or anything. Is there anyway to just totally screw that computer up? Anything. Paybacks a bitch. Thanks.

i heard if you open command prompt and enter formatC: it will wipe it. try it, it might work.