My test client is an HP dc7600 CMT w/ 1GB memory. Here's are the times
I'm seeing for unicast/multicast of a 2GB image:

Ghost: 4 mins / 4 mins
ZEN: 8 mins / 68 mins

Ghost is running on PC hardware. ZEN is running on an HP dl360 G5. I'm
using the Feb 2010 driver update for PXE but haven't applied any hot
patches to the server yet, so ZEN is still at SP1IR4a.

Network folk are looking at the switches for me. After that, I'll look
at patching ZEN to HP3/retesting.