If you would like to install Windows Server 2012 Release Candidate (including Windows Server 2012 Essentials) on to a HP ProLiant server, then HP have a handy PDF document for you.
The 12 page PDF includes pre-installation tasks and installation instructions for supported HP ProLiant servers which include the ProLiant MicroServer
Also included are known issues and their workarounds in this handy technical white paper which you can download from here.
Implementing WS2012 Release Candidate on HP ProLiant Servers is a post from: MS Windows Home Server - Your Personal Guide to Microsoft Windows Home Server!
Microsoft MVP Philip Churchill's MS Windows Home Server Blog is one of the leading sources of breaking news and information, insightful opinion, and great tutorials regarding Windows Home Server. If you're an HP MediaSmart Server owner, this is a can't miss!