I had one drive of a RAID 0 array die on me. My plain is to reinstall Vista on the surviving drive. When I get to the point where I choose which drive to install on, my only choice is a recently installed 2TB hard drive that contains all of my backups, which I obviously need. The drive does show up in BIOS and in diskpart, just not in the Vista install program.
As long as the RAID controller does not see the drive as being part of a RAID set, Windows should see that single drive. Check in the RAID settings to make sure the drive is not seen as part of the array.