OK, Macs use what is called an EFI, which is like a new-age BIOS. EFI has the ability to emulate a BIOS, which is primarily what BootCamp does, it allows the EFI to emulate a BIOS (something that I believe is turned off by default)
You will have to provide your own copy of Windows XP SP2, or Vista.
When you run teh BootCamp Assistant, it allows you to partition your drive, then, you restart with the Windows disk in the drive, and install it like you would any other computer. When it is done, you drop in your Leopard disk and install the BootCamp drivers.