Sony Vaio Laptop. Enable raid sata, help needed please.

Hello.
My girlfriends mum took her laptop to pc world as one of the
hard drive was at fault. He removed the hard drive and disabled Sata,
so it only looks at 1 drive on boot. Now I have a new (2nd)hard drive
and want to enable sata raid again, so the laptop can have two drives
again. Thought the option would be in the bios,but I'm just not seeing
it. Please could someone point me in the right direction?
Its a sony Vaio VGN-AR21S. Running Windows Vista operating system. 2
Duo processor T7200. 2 GB/go DDR2 SDram.
Would be very grateful of any help.
Kind Regards. Paul