MissingRemote posted a guide about upgrading HP WHS MediaSmart EX495 to Windows Home Server 2011

Those of you who have been following our MissingRemote Podcast are familiar with the dilemma I have been facing for the last few months--do I dare take the plunge on my one and only Windows Home Server system, based off of an HP MediaSmart EX495, and upgrade to the new and "improved" WHS 2011? After much deliberation and non-stop harassment from, well everyone, I decided it was time. The process was not nearly as bad as I had anticipated but the results are certainly mixed. Obviously this upgrade is not supported by HP given that the EX495 is long since discontinued, but migrating it to WHS 2011 would hopefully be worth the upgrade.

  Upgrading HP WHS MediaSmart EX495 to Windows Home Server 2011 Blog