I've been using the BARTPE stuff for "Donkeys years" but wanted to see if there was something newer.
This works fine . This is based on VISTA but hopefully a Windows 7 version will come.
It's a bit fiddly but use re-writable media and then you can have several goes without wasting a lot of media.
It basically builds a Bootable Live DVD environment which doesn't run off your "C" or windows drive.
You can add plugins / other programs.
Excellent for recovery of broken systems etc etc.
Beginner's Guide to Creating a VistaPE CD
(If you are creating this from an X-64 system download and install Microsoft WAIK first or it*might* not work correctly - depending on your choices.
Examples refer to build 074 of winbuilder -- later build is 076 --not tested but should be the same or at least very similar -- build 074 of winbuilder is still current and available however).