You can't wipe a disk while Windows is active. So you need to boot from either a cd or a USB-stick.
For wiping we recommend DBAN. You can download an .iso file that you burn to CD (using imgburn, for example), but http://www.pendrivelinux.com/install-dban-to-a-usb-flash-drive-using-windows/ tells how to make a bootable USB-stick from it.
If that doesn't work, see if you can replace the CD-drive by one that does boot, or use a USB-connected external drive.
Kees
I need to delete everything on my hard drive (command + space + c:), as I bought a new computer. I tried pressing F8 or f9 during startup, but the menu that appears doesn't contain a pure DOS prompt. I have the XP CD that came with the computer, but I may be having cd disk drive issues and it will not boot from the CD. help!

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