http://blogs.technet.com/jkruse/archive/2007/01/29/exchange-2007-platforms-editions-product-keys-and-versions.aspxScott Schnoll has a great post on the differences between the various versions of Exchange 2007. He also sheds light on one of the most commonly asked questions - can you upgrade from the Trial version to Retail? (the answer is yes ) http://blogs.technet.com/scottschnoll/archive/2006/12/31/exchange-2007-platforms-and-product-keys.aspen-USCommunityServer 2.1 SP1 (Build: 61025.2)