You may well find that your mass storage controller requires a driver so that XP installation can continue...
ie: During the first phase of the Windows XP installation, Setup displays the following message at the bottom of the screen:
Press F6 if you have to install a third-party SCSI or RAID driver.
Press F6 and then follow the instructions to install a mass-storage device driver from your Original Equipment Manufacturer (OEM).
This is a common reason for showing that STOP message.