Installing XP Prof on computer w/o OS.

How do you install Windows XP Professional on a computer that has no OS? I built a computer and got Windows XP Professional as my OS, but no partitioning or formatting disk came with it. Can’t install XP in DOS using a 98 start up disk, The WIN XPCD will not run in DOS. Will the WIN ME start up disk work? How do I get a start up disk for WIN XP? Having to create one doesn’t seem logical.