Win XP install cant see sata hard drives

Hi,
I have a question that I would appreciate the answer to if possible.
I’m trying to install Win XP home an my PC but setup cant find any hard drives on the system so wont continue.
I have 2 sata drives that appear in the bios ok.
I have a Asus K8vSE MB, AMD 64 3200+ CPU and 2 Via sata drives, one 160gb and the other 120gb.
Been racking my brains but just cant figure out the problem.
Any help I would be indebted for ever.
Thanks in advance
Pete