I have a lab of machines with 3 NTFS partitions, which dual-boot two different WinXP Pro installations (one on each of the first two partitions) with the third being a shared data partition. I need the boot/system partition to be C:, the data partition to be D: and the other bootable partition to have no drive letter allocated. (I also need the CD drive to move up to become J:, but I've already done that using a Diskpart script.) The problem: Diskpart appears to accept the commands to remove the drive letter from the second partition then allocate it to the third instead - but on reboot, they're back to D and E as before. Any suggestions? It looks like I can win half the battle with a registry hack (just copying \\DosDevices\E's mount entry over \\DosDevice\D's) - but upon reboot, XP will regard the 2nd partition as 'new' and allocate it another letter instead. When the Disk Management tool removes the drive letter, it seems to give the partition a GUID prefixed with a # as a mount point - I though just putting 'UNUSED' would be enough to stop XP thinking it's a new device, but no...