AMD64 Files?

[gadget]

I use WinPE 1.6 everyday in work and we now have HP systems with the AMD64 on board. Though most will boot to winpe (Via RIS Server) some don't. In the PE cd there is a directory for the AMD64 with different files. Where do I put these files in the PE image or do I have to create a totally seperate PE image and replace these files> PE Help document is very forthcomming...

Thanks