WMI Filter for 2008 R2 OS

Hi,

I'm currently trying to find a WMI Filter/Query to use with GPO's that will only impact Windows Server 2008 R2 Servers.

I have noticed plenty of WMI Filters that hit certain "versions" of windows (e.g. 2008 R2 AND Windows 7, as per http://social.technet.microsoft.com/Forums/windowsserver/en-US/a5438b5a-13f0-4b0a-9f49-e99942657c49/wmi-filter-for-os?forum=ITCG), however, i would like to ensure that the WMI filter is specifically for the Windows Server OS (regardless of the service pack level on 2008 R2)

Would someone be able to assist me with this please?

Thanks in advance