I had a RAID 0 on my P5B Deluxe WiFi/AP with the Intel ICH8R and upgraded to the Rampage Formula with the ICH9R and I did not have a problem. I just set the SATA to RAID and then go into BIOS and set RAID to boot and Presto it booted. I had to reactivate Windows but it did work.
But I do not recommend that unless your MB dies. and you can recover your files and then reformat.
My P4C800 deluxe dies I have 2 200Gig IDE drives in a RAID on the Promise PDC20378 controller. To recover from that I had to purchase Active@ File Recovery and rebuilt the RAID via software and recovered the files.
Toms did a RAID upgrade artical http://www.tomshardware.com/reviews/OPTING-RAID-LEVEL-MIGRATION,1594.html
This may help