Went to stand up Office 2010 KMS server on an existing 2008 server. I went to install Office 2010 key management host and I get “Unsupported Operating System”. So I decided to install on 2003 license server again already existing and I get the same error. I run the key management host on my windows 7 computer thinking maybe I received a bad download runs with no issues. So after some digging threw office 2010 beta and official release documentation and a few Google searches I found out some very interesting information. Office 2010 KMS only runs on Windows 2003, Windows 2008 R2 and Windows 7 all other operating systems are not supported. Microsoft has released a patch to help those still running 2003 KMS server. But so far no patch for the 2008 server the only fix I have found for that is to upgrade to R2.