that's right. On my MoBo, I use the "F11" key to call up a boot menu showing all available boot devices, yours might use a different key, or may not have the feature at all. Find out if it has it, because if it doesn't you'll have to enter the BIOS everytime you want to boot the second OS (and that would get old quickly). If that's the case, you'll be better off installing the OS with both drives connected, XP first and Vista second.