Without formatting and allocatin a drive letter, it won't show in My COmputer but it should appear in Control Panel>Administrative Tools>Computer Management>Disk Management. You can carry out both those operations in there.
If you haven't installed XP yet and Setup is failing, it's almost certainly for want of SATA drivers for that disk. Try again and press Function 6 when prompted in the early stages and when the setup stalls for the driver, press Enter. That forces XP to look inside itself for more drivers.