might be a stupid question but if asus dont post a driver then serial ata is probably done by the bios. Have you checked the bios and made sure that the serial ata controllers are switched on?

Sometimes with an Asus board, if you boot from the motherboard CD it often offers to make a serial ata floppy for you.

is it a serial ata drive?
Usually when loading xp you need to press f6 pretty early on in the setup and have a serial ata driver disk from your motherboard manufactorer. Then your hard disks will...