I found this page which deals with hot-swappable hard drives
I had vista formatted first and then put in the second drive and put xp on.
Then Vista wouldn't boot, so I did a repair on vista, now vista boots but xp doesnt
The article says that vista has a bootloader that overwrites the xp.
now I'm wondering if I repair xp if it would make vista not boot
I'm not sure I want to spend the time, experiementing