Sadly, I have Cox, as do most of my friends and relatives who have HD screens.
Where I live is all fiber optics, but the HD news, Discovery HD, all of what I've seen in my area looks bad. Kind of like an overly compressed digital camera image. Artifacts and compression are very noticeable. Even on a standard TV, I see compression now days, and of course sometimes the image will scramble into boxes as the stream rebuffers. It's quick, but still annoying.
This gives me hope; (The 720P trailer is very clean, even better then the Batman 1080i trailer.) http://www.apple.com/quicktime/hdga...omofheaven.html
So hopefully Cox will start streaming that kind of quality, then I would be happy with a HDTV.