I downloaded that file but haven't done anything with it. Is it needed? It is the same as the files that are already in c:\windows\policydefinitions? Because if I look in c:windows\policydefinitions there are a bunch of ADMX files. This is
what you are talking about. I should copy these over to c:\windows\sysvol\sysvol\contoso.com (our domain name)\policies\policydefinitions\
What about policies that are already there? I shouldn't lose them by making any of these changes should I?
When you first create the CS folders on SYSVOL, they are empty, but the mere existence of the CS will force GPMC to defer to the CS to look for templates. This is why you need to place a copy of all the Windows templates plus whatever Office/other templates
in the CS.
It's simplest to copy the Windows (and any other templates) from c:\windows\PolicyDefinitions into the CS - you don't specifically need to use that download files set of Windows templates.
Once you've established your CS, you can then consider if you need to download newer Windows template files (e.g. the newer templates to suit newer Windows edition features), just replace any existing files in the policydefinitions folder with the newer
versions.
Note that in general, Windows templates are not Windows-version-specific, but Office templates *ARE* version specific, so if you need to have settings from the Office2010 templates, and say you also needed to use settings from the Office2013 templates, you
need both sets of templates to cater for both version of Office. (they are different filenames for the Office templates)
Also note that templates are what defines the available settings, but templates don't contain the actual GPOs/policies in your domain. When you author a GPO and into that GPO you open a template and enable a setting, the actual setting, and the values you
assign to the setting, are actually written into the GPO (the GPO is stored in a different place in SYSVOL/AD, it's not stored in the policydefinitions folder at all)
This is similar in concept to a Word template compared to a Word document, i.e. the template doesn't contain your document content.
And yes, SYSVOL is replicated across all of your domain controllers, which is how the templates CS is deemed to be "central", because it's placed once and then replicated around for you.
And, don't use ADM files in your CS - the CS is only used for ADMX/ADML files. (ADM files are the pre-Vista form of templates).
ADM files, if placed in your CS, won't work, and they just waste space on SYSVOL.