One of the primary reasons to use Disk Director is to have more than one OS on the same HD. I have one HD with 2 XP Pro OS's installed, each in their own primary partition. Background one HardDisk OS #1, installed as Primary on Partition #1 OS #2, installed as Primary on Partition #2 OS #1 boots up as C:, while OS #2 boots up as D: . The registry in the OS #2 also references D: . I've been looking for a clear answer, but still confused on how to ensure that each OS always boots up as C: . I am willing to re-install OS #2 if necessary, but how can I make each OS always boot up as C: when it is active? I am using Acronis OS Selector on the first partition. Do I need to install this on each partition? Is it possible to have each OS always boot-up as C: ? I don't care what letter shows for the non-booted OS and I know I can change this with the Windows Disk Management facility. But the currently running OS must always be C: as I will be copying settings from the first OS to the second OS and need to maintain path integrity. Thank you!