What kind of RAID array, software or hardware? In any case, it is possible; it all depends on which drives you choose to build the array. Check your mobo documentation first; it says if it's RAID-capable or not.
When re-inststalling the Windows XP Home Edition you have to load the SATA drivers from a floppy using the F6 key. Windows XP does not have native SATA drivers. There is a way of adding the drivers and updating the Registry manually to enable them if you cannot re-install the OS.