That motherboard uses a Promise RAID controller. Did you configure a RAID 0 or a RAID 1? If RAID 1, then each hard disk should still contain all of the info. If RAID 0, you need to use the same motherboard or buy a controller with an identical or a very similar Promise controller.
I have tried to look at each drive by connecting to another machine but they show as foreign so I guess it must have been raid 0 ( We originally put it together to run photoshop so maybe done for speed ?) I found another KT 4 Ultra on eBay but there seem to be versions of this board that don't have the raid support.