1. Group Policy ADMX and ADML
Configuration of a central store

2. Overview Group Policy Overview .admx and .adml files
Group policy integration
Local
Central Store
Benefits
Limitations
Video

3. Group Policy
Prior to Windows Vista/Server 2008 we used .adm files in group policy
Proprietary file format
Requires that administrators have a local copy of all .adm files
Requires copying of the adm file to specific group policy object sysvol\domain\policies\<GUID> directories
About 2MB in size, causes lots of replications issues. (2MB * 1000 files = 2GB of network traffic)

4. .admx and .adml
Newer group policy object files based on xml and supports language specific variants (.adml)
Supported natively by Windows Vista and later operating systems
Smaller foot print than previous .adm files

5. Group Policy Integration
Local Store
%systemroot%\policyDefinitions
Central Store
%systemroot%\sysvol\domain\policies\PolicyDefinitions
Both work with Group Policy Editor on Windows Vista and later

6. Benefits Advantages of using ADMX Central Store:
Once an admx file is added to the central store, it is available to all group policy administrators
Reduces the amount of replication across the domain controllers
.admx and .adml files are about 1/10th the size of .adm files
Central store is only copied once

7. Limitations
Only Windows Vista and later operating systems versions of group policy administrative console support admx and adml files
Administrators cannot use a Windows XP or prior operating system to administer group policy, including Windows Server 2003 R2 and earlier server versions
Will break custom modifications directly made to the following files
System.adm
Inetres.adm
Wmplayer.adm
Wuau.adm
.admx and .adml files for Windows 7 and 2008 R2 are not necessarily compatible with group policy editor for Vista and 2008.
.admx and .adml files must be located either centrally or locally to apply correctly

9. Notes http://technet.microsoft.com/en-us/library/cc709647.aspx