Does the desktop machine has any removable drives? Probably those are already given the c: and d: driveletters. Most likely your old WinPE didn't recognize those. To start 'clean' try running the diskpart /s x:\ldclient\rmvolltetter.txt as one of your first actions. Than, after you restore the images, use partition actions to mount the c and d drives on the right partitions.
looking at x:\ldprovisioning\diskpart.txt i notice it is now stating: assign letter=N
this is part of the new Win8 PE right?
any reason why this is hard set?