Steve,

The MediaMVP can not play HD. The OTA file will be transcoded* by SageTV to an SD resolution. The maximum resolution the MediaMVP supports is 720x480 MPEG-2 (DVD Quality). So you need a powerful server to do that. I'm not sure how much horsepower is needed, but I would suggest a fast Core 2 Duo, Core 2 Quad, Phenom X3, X4, Phenom-II or Core I7. Some of those may be overkill.

*Transcode: Real time video conversion.