Why not replace your ATI box (sell) with a SiliconDust HDHomeRun Prime? It's device independent, comes with 3 built-in tuners, cable card slot, and connects between the coaxial cable and your network hub/router - not a computer. It even comes with tuning
software that you can install on multiple computers and mobile devices.
Here's info on that device:
https://www.silicondust.com/product/hdhomerun-prime/
About Windows Media Server, it's the first time I've heard of it even though it came out in 2008. I found the following release notes page:
https://technet.microsoft.com/library/cc771560.aspx#wms_010
I found the following installation information which mentions installing WMS on Windows Server 2008, Vista, and Windows 7:
https://technet.microsoft.com/en-us/library/ee822833#Managing a Windows Media server
If I were you I would just try to install it on WHS 2011 if you have WMS on a network share or portable media. I hope this helps.
ENJOY!©
