I am currently facing a little problem with my HDMI to HDMI connection from my PC (Lucid AMD Radeon HD 6900 Series) and my old HDTV (LG 32 LC52-ZC).
I think that the resolution of my TV is 1366x768 but when connecting with HDMI cable, I have a 1360x768 resolution.
But my problem is that colors are a little bit dull on desktop, but extremely faded in-games (it's almost grey) and in 1080p resolution colors are blinding and extremely shiny (if I may say, I hope you get the point)!
I thought that DVI or VGA would be better, I don't know, waiting for your advices!
More abouthdmi resolution problem 6900 series
Right click your desktop and open AMD VISION Engine control center there are different display options that you could try change to achieve what you want.
In your Catalyst Control Center, Common Display Tasks, Detect Displays. This should help. Probably DVI would work better on an old HDTV because hdmi standards may not have been finalized when it was built.