You can't do it from there... you have to get ahold of a copy of FDisk, and then use this. You have to delete the partition, and then it will destroy the data on that partition. From there you recreate it, and then let it do its deal. After this you restart, insert the Windows XP CD, and voila.
A+ Core Hardware, Software Certified (May 13 2005)
the new beast...
AMD Athlon XP 3200+ Barton running at 2.16 Ghz.
GeForce MX 4000 (mainly takes the load off the main system)
Creative Labs Audigy 24-bit sound.
Some Case from tigerdirect
512 MB Ultra DDR RAM.
80GB Seagate HDD
LiteOn CD-RW / DVD ROM drive.
currently looking at a litescribe drive at staples, due to its ability to label the CD shortly after being burned.