Some time ago we had some issues with the WDS Image Capture Wizard that WDS inserts into WinPE to create capture images . When we got to the screen where you select the drive letter you want, the WDS Image Capture Wizard didn't list the drives, not even the C: drive. We could get to it using the command prompt, though, so we created those test images by running imagex manually.
Well, it turns out that we were just documenting the processes at the time, with a full OS install on the hard disk. In what could be described as a RTFM moment, we finally figured out what was wrong – the WDS Image Capture Wizard only lists Sysprep’d drives. Once we ran Sysprep on the OS installation, everything worked smoothly with the Capture Wizard.
The moral of the story is that sometimes it pays to read the manual (and follow the instructions) before jumping head-first into a project. 