Many people have trouble with Windows stock recovery/backup program. It should not be relied upon.
It may be too late, since you already changed to RAID in BIOS, but this may be worth a shot. Change back to single disk in BIOS, and try the Windows recovery disk. If that fails, try the repair option from the Windows install CD.
In order to use a free program to image a RAID array, you need to be running in Windows, or some OS that will recognized the fake RAID. I don't know of a free imaging program that will recognize a RAID array with it's recovery CD. You can get around this by installing an additional hard drive, and putting a bear bones XP OS on a 3-4Gb partition on it. On the XP drive, install Partition Wizard, Macrium Reflect, and Auslogic Defrag. These are all free. If you can find it, also install Paragon Alignment Tool. With these tools, you can work on your Raid array.
When you have Windows running again image your OS partition to your USB drive, and also to the single drive with your XP install (if you didn't just use the USB drive for the internal, XP drive). It wouldn't hurt to make 3 or 4 images to be on the safe side- but honestly, the only time I never got an image file to work is after I moved it, or let my defrag program go to town on it.
With a valid image file, you can switch to RAID on the first two disks in BIOS, than boot to the XP disk, recover an image to the RAID array, and align it. Now you should be able to boot normally to Windows on the RAID array.