Pre-Windows Server 2008, ADM files were used to extend Active Directory group policy. In Windows Server 2008 that changed and now ADMX/ADML XML-based files are used for that purpose.
Legacy ADM files can still be used with Windows Server 2008, but it’s probably a good idea to migrate any ADM files to ADMX. This can be accomplished with the FullArmor ADMX Migrator tool.
The ADMX Migrator tool is a Microsoft Management Console (MMC) snap-in, which, using a graphical user interface, allows the creating and editing of Administrative templates and converts ADM files to ADMX format.
The tool downloads as an MSI file and the install is easy and quick.
To migrate an ADM file to ADMX, after downloading and installing the ADMX Migrator tool, launch it from the Start menu, click the Action menu item and select ‘Generate ADMX from ADM…’
Select the ADM file to migrate to ADMX.
It quickly converts the ADM file to ADMX.
And shows the results of the ADMX conversion.
It asks if you want to load it in the ADMX editor.
If you choose Yes it opens the newly converted ADMX file in the editor.
That’s how to convert an ADM file to ADMX. Very easy huh?