I would like to use the HORM feature of WES to allow a fast boot time, this requires me to use EWF.
Can I use EWF to protect only my C drive and write any application data to the D drive.
As such I can then boot quickly with the HORM feature but still have all previous application data available on the D drive from my last session?
Yes, you can do this, but you must implement a solution described in this article to preserve data on the D drive:
www.sjjmicro.com / www.seanliming.com, Book Author - XP Embedded Advanced, XPe Supplemental Toolkit, WEPOS / POS for .NET Step-by-Step
You need to dismount the unprotected partitions before you capture the HORM image (when you hibernate for the first time). To dismount volumes you can write a custom application (as described in the link posted by Sean above) OR you can use mountvol.exe. This binary ships as part of Windows XP, you might want to do a little searching to see which XPE package contains this. Its usage is documented here. I came across mountvol.exe recently and haven't used it myself, but it might be worth trying first , before writing a custom application.
Srikanth Kamath [MSFT]