You will lose everything on both discs. Everything.
Make sure you have the correct RAID drivers for your controller on Floppy.
If you have XP, you will need to have them, or XP will not be able to see the array. If you have Vista, you should not need them, but never the less, put them on a floppy now, before you do anything else.
Simply enter the RAID BIOS, (look for the message during POST)
Break the array, rebuild the 2 disks into a striped set, or RAID 0.
This also will basically wipe everything off both drives.
Reboot, and prepare to reinstall your OS.