LOL Put the Windows XP cd in. Re-boot it again, and when it gets past the hard drive diagnostics, it should say, "Press any key to boot from CD...." and just press enter or whatever. And Windows setup should start and you can format & partition the hard drive or whatever. Don't worry we we're all once noobs to this stuff.
BTW Welcome to CF! Haven't seen you around so I thought I'd say Hi.