JCL, I think your DVDs look worse than the HD channels because of three possible reasons:
1) The DVD player doesn't put out 1080 horizontal lines.
2) The DVD player isn't connected via HDMI or component HD.
3) You're watching an older DVD, which is 720 or 480 horizontal lines.
At first I was running my usual $120 Samsung DVD player with the HDTV through stock composite connectors. That looked no more impressive than on the Sony tube I had.
Then I installed a $300 Samsung DVD player which was HD, and put out 1080 lines. But even with this player, through composites it looked no better.
Now I'm running that DVD player with 5 HD composites (red, green, blue, audio left and right). Now it's nearly on par with the HD channels themselves.
I wish we could get some 1080-line DVDs, cuz as per your observation, the HD channels still look better.