Thanks go to Pritesh for helping me out with this one.
I was trying to provision a 64-bit X4200 with the Provisioning Manager.
The Server was spitting out a BSOD with the following message "Stop: 0x0000005c (0x0000010b, 0x00000003, 0x00000000, 0x00000000)"
We googled the error and found that it normally shows up for the X4200 because the BIOS needed an upgrade.
Upgraded, started provisioning, and it got through this time. Now, WinPE actually starts.