[Raid762]

If your bios is detecting the drive as 200gb then it sounds like you may have created your partition incorrectly .
If you have got XP running on your system right click 'my computer/MANAGE' and select disk management. You should see your current drive configuration , with perhaps a 30gb partition and lots of free space.Try using this tool to reconfigure the drive if this is the case.
As for data recovery , I have just been through something like this after replacing my motherboard a couple oy my partitions dissappeared , after recreating a partition on the blank space and formatting I used 'Recover my Files 3.06' and recovered most of the stuff that was there, although I had to do a lot of sorting to identify what I had recovered.