it's because the SATA port on your board is controlled by a external chip so it's not natively recognized. WHen you boot from the XP cd, it should say "hit F6 to load scsi driver" Hit F6. After it finish loading the rest of the drivers it'll ask your to specify a scsi controller. Insert the floppy for the SATA RAID controller that came with your motherboard into your floppy drive and click "S" It should scan the CD and load the drivers than windows will recognize your drive.
Also you may need to got into the Bios properity for the Controller ans specify it as a single drive. When you computer boots there should be a screen where it detects your Drive, not the initial boot up screen, hit whatever buttom you need to get into the option menu, it'll tell you which keys to hit.