Network traffic and the ADMX central store
Here's a tip concerning planning for network traffic when you implement a central store for ADMX template files. Unlike ADM template files in earlier versions of Windows, ADMX files are not stored within individual GPOs by default. However, administrators can create a central store of ADMX files for the domain that can then be accessed by any client having permissions to create or edit GPOs. KB 929841 has information on how to implement a central store for your environment.
However, if you do create a central store, you need to be aware of the increased network overhead this store may need to handle. Specifically, the client will read the ADMX and ADML files from the central store every time the Group Policy Management Console is started because GPMC has no mechanism for caching the contents of these files. And RSoP reporting in the GPMC uses the ADMX files in the central store to translate registry values into policy settings, so each time you perform RSoP reporting with the GPMC the central store needs to be accessed as well.