drive empty?.. if it is, make it the C: drive. don't even hook up the original drive. Treat the second install as a new install. Once this is acieved, re-install the original as the C: drive, re-install the second drive as the d:. Go into setup and change boot device priorities. However, setup may not allow boot from two harddrives. I am assuming you want the second OS in case the first fails for some reason. If your BIOS won't set to second harddrive as bootable, you'll have to change cabling again to put second OS as primary <master>.
Is this what you are talking about??
and life goes on...
Could someone point me towards the walkthrough instructions for having XP installed twice, once on each of two hard drives so I can choose which one to boot at startup? I know I should be able to find it by searching but....I can't!