I would say, always backup before you upgrade, but I'm not sure how helpful that would be now. I've moved from different ICH chipsets keeping my RAID in tact, but I've never tried it with a boot device. Here is my concern. It sounds like the BIOS doesn't see one of the drives as a RAID member, which would tell me that it doesn't recognize the RAID signature on the drive. There is a possiblity that you could have corrupted one of the drives during the move...it's happend to me.
I would try rebuilding the system with the old motherboard to see if it's recognized still. If it is and it boots, then your ICH10R has an issue with it. I'm not sure what Intel says about compatibility across chipsets...so I can't say if it's possible to transfer from 9R to 10R. As I said, I've done it, but I don't remember from what to what.
I would see if you can get the old system up with those drives again, then back it up. Then get the new motherboard in and make sure you have a recent BIOS. If all else fails, rebuild the raid and restore.