Well, Server 2008 required Hardware Virtualization to run, and also won;t run off of a USB disk most likely.
also, just a note, i've sat the 680 exam twice and failed. Theres barely any Server stuff in it. Cram deployment, CRAM IT DAMN IT.
edit: also, Since Server 2011 was released, you can't buy Server 2008 licenses anymore i dont think.