Like people have said, to get a good amount HDtv, you need a sattellite HD tuner, or an off air HD tuner. You can probably get the off air hdtuner for under 500 dollars. And you can use old style antenna outside of the home to get local channels in HD. That is all that I have to add...
Also for help with this and other HD concerns, check out
www.avsforum.com.