Is this a newly fitted drive?
does the board support SATA2?
Sata Drive not recognised by BIOS
SATA 2 (SATA 300) is not backwards compatible with a SATA (SATA 150) controller. In order to use a SATA 2 drive on a SATA (SATA 1?) controller, the hard drive must have a jumper position to restrict it to using SATA (SATA 150), and a jumper must be installed. Some drives have the jumper position available (e.g. some recent Samsung), some don't (e.g. some recent Maxtor).
This information can also probably be easily found on your hard drive manufacturer's web site.
If your drive does not have the jumper position available, you must return it and get a SATA 2 one that does, or a SATA drive.