Actually, looking at the specs on the Gateway 50 inch plasma TV, it also does not do HDTV resolution either. From their FAQ...

I believe that section of the FAQ is referring to hooking up your computer to the TV itself - not to HDTV compatibility. Technically, the TV is HD because it fits the "vertical scanning lines of 720 progressive (720p)" requirement - but it must use the scaling for all 1080i HDTV formatted broadcasts. The other Plasma TV's that gateway offers have a much smaller resolution and use the digital scaling to reduce the signal down to 852 x 480 for both 720p and 1080i - as outlined in their additional specifications for the smaller plasma TVs.

- trs