WIN PE is a slimmed down thing. At no time would I expect it to give me full chip and USB support.

And there's the rub. You will find machines it works on then not.

Parting idea. Check the BIOS for LEGACY USB support.

Second parting BIG idea. I don't use WIN PE anymore. Why? Read:
http://tips.oncomputers.info/archives2004/0401/2004-Jan-11.htm