With Windows Server 2008, Windows Vista, and Windows 7 Microsoft changed the group policy template files to an XML format (.ADMX file extension). These files are stored in the PolicyDefinitions folder under %systemroot%. If you open the Group Policy Editor from a 2008 or higher system, it will automatically access these files on the local system. However if you want to automatically have access to the templates across the network you can create a central store on a domain controller and they will be automatically replicated with other domain controllers in the domain. Using this method I was able to make the newer Windows 7 ADMX files available on our 2008 domain controllers. [more]
http://technet.microsoft.com/en-us/library/cc748955%28WS.10%29.aspx