OK, I'm running XP SP2 on the rig in my sig with an Antec 550W PSU and Windows is booting from a SATA drive but now and then, when it gets to the Windows screen with the black background it will permanently freeze, requiring a manual reboot, any idea what this could be? I try and maintain my rig well with all the latest mobo/graphics drivers etc, oh and the motherboard is an ASUS P5N32-E SLI and other than that it seems very stable.