Are you using onboard raid controller or an cheap ad in card. Cause it sounds like the raid array your trying to load windows to isn't bootable. This is an option you must enable in the raid bios when setting up the raid.
If it's onboard it should be bootable if you configured the raid correctly if it's a cheap addin card it may not support the bootable feature and you need an extra hard drive to house windows 7 100mb hidden partion for booting. I had to do this when i had a cheap raid card till i upgraded to a better board.