Switched Disk Config to IDE, can't switch back.

I've had my computer since March of 2008 and four days ago it froze and refused to boot up again, always getting to the Windows XP loading screen, progress bar moving, and staying there for, say, a half hour before finally giving up and going completely black. In the pre-boot hard drive screen, I saw that my C: drive, a Seagate 500 GB, had suffered a SMART Event. My E: drive, two Seagate 1000 GBs striped in RAID 0, was apparently fine.

Earlier today I bought a Western Digital 500 GB to replace the SMARTed Seagate. Unfortunately, my computer uses SATA and has no floppy drives, so the Windows XP boot disc wasn't able to read the WD drive and I couldn't use my RAID/AHCI Driver floppy to enable it to do so. Following advice I found online, I switched the Drive Configuration in the BIOS from RAID to IDE, which allowed me to install XP onto the Western Digital. The aforementioned advice assured me that I would be able to switch back to RAID without problem.

Unfortunately, I can't. Trying to boot the computer in anything but IDE causes an inescapable restart loop when the computer attempts to boot and of course, booting in IDE prevents my E: drive from being read correctly by the computer when it is on.

I very much appreciate any help anyone can provide. I truly do need to get my E: drive running again as it contains all of my irreplaceable documents and such (I do realize it's dangerous to have irreplaceable documents on a RAID 0 volume).

Thanks for reading, desperate for advice,

Jason

I am running:

Windows XP Home SP2
Intel 2 Duo CPU E4500 2.20GHz
4 GB RAM
ATI Radeon HD 2600 Pro
Optiarc DVD RW
Western Digital 500 GB
Formerly: Seagate 500 GB (now dead), Two 1000 GB Seagates: RAID 0.