as dgramc said, I’m pretty sure as long as the TV is “hd ready” it doesn’t need a built in tuner to display hd info. The built in tuner is more of a conveinence so you don’t have another piece of equipment to hook up. Also, make sure you have enough high def inputs, like 2 hdmi or dvi, so that you can get the best signal from both the HD cable box, and your dvd player.
At least that’s how I understand it…