A little tidbit that I learned while researching the 760/E6400 issue (This is from Michael Kelley [MSTF] over at the Technet Forums):
"You can deploy an x64 operating system from a 32-bit WinPE. This combination allows you to use a 32-bit WinPE, run various hardware tools (such as doing BIOS configuration, configuring a RAID controller, etc.) as task sequence actions, and still deploy an x64 operating system. Many of these tools are 32-bit executables. x64 WinPE does not include the WOW layer that full x64 Windows has, so it can't run 32-bit tools.
Deploying a 32-bit operating system from x64 Windows PE is not supported..."
Link to Post: http://social.technet.microsoft.com/Forums/en-US/configmgrosd/thread/e446b57b-cae0-4cc8-8d41-97007825687d