Very nice laptop!
You need to install the sata drivers on that partition so that xp can see the drives.(2.5" 9.5mm SATA harddrive specs)
Download the XP driver files for the Sata harddrive. and put them on a CD. Reboot with the XP installation disc and watch closely for the prompt..."Hit F6 to load any third party drivers.." press the F6 key and follow the directions!
You just might have major issues trying to find drivers for windows XP.
Here is your driver download page.... ASUSTeK Computer Inc.-Support-
that computer has no listing for any XP drivers at all so good luck with it.