RAID can't find drive, slow drive

When I upgraded my computer from an Athlon 64 x2 6000+ to a Core i7 960, my computer became slower!

I have 2 500Gig SATA drives that were in a mirrored RAID array (which is it, 0 or 1?) before the upgrade. Like the old motherboard, the new motherboard, Asus P6T, has an on-board SATA RAID controller, but the RAID bios told me there are no drives attached. Obviously, that is not true, since I am able to boot from one of the drives.

Since I couldn't get the hardware RAID set up (I did try the software RAID set-up, with the same results), I am using Asus's software solution called Asus Drive Xpert in EZ Backup mode, which works, but I think it is the source of the slow-down.

I can think of 2 possible solutions:
1. Decide the motherboard's RAID controller is defective, and replace the motherboard.
2. Decide the drives are defective, or the existing raid configuration on the drives was confusing the RAID controller, and buy new drives, leaving the old drives as storage. I don't want to lose what's on the drives, so reformatting isn't an option.

I don't want to waste time and money choosing the wrong option first (as I have a history of doing).

Can you guys help me decide which option is the correct one, or find a third, better option?

If you need more information, ask away! I'll be happy to help you help me.