Stu;
..ADM files are template files that are used by Group Policies to describe
where registry-based policy settings are stored in the registry. ADM files
also describe the user interface that administrators see in the Group
Policy Object Editor snap-in. Group Policy Object Editor is used by
administrators when they create or modify Group Policy objects (GPOs).
http://support.microsoft.com/kb/816662
Use notepad to edit (look at) your C:WINDOWS/inf/windowsdefender.adm file,
scroll to the bottom and you'll see the explanations for the GPO controls.
Close that notepad window without saving when your through. I know what it
does, but have never done it, so perhaps a Sysadmin can add more...