About the 768 resolution, that's the correct guess, that's to ensure compatibility with 1024*768.
It's not that much of a problem if the LCD is 1366*768 because its still almost 16/9 and the upscalling from 1280*720 to 1366*768 won't be seen in most case.
The real problem is that a lot of 16:9 tv like my philips chose a native resolution of 1280*768 = 15/9
15/9 resolution on 16/9 tv...
The HD IPTV receiver send (in this case) a HD image of 1280*720. Since the screen resolution is 1280*768, there are black screen (small ones) on top and button of the screen and to conpensate, the tv zoom in the picture.
Result : Loss of something at the right and at the left, and wrong aspect ratio.
If the native is 1366*768 (and the tv is well configured to minimise overscan), you lose almost nothing (even nothing with perfect config) and aspect ratio is 1.7786.
16/9 = 1.7777 So i dont think you can see the difference.
My conclusion. STAY AWAY FROM THOSE CRAPPY 1280*768 SET.
With my philips, i manage to compensate the 15/9 problem by using a computer as a source to play video. I force the aspect ratio of 16/9 material to 15/9, that way, no part of screen lost and no black borders.
Sorry for some mistakes i may have made, i'm french and not fluent in english yet.