There are two standard resolutions of high definition - 720 and 1080. The 1080 is a higher resolution by about 15 - 20% but most live sports events are shot in 720. Most people will not notice much difference between 720 and 1080 at the normal distances they will sit away from the TV.
Another choice to make is whether to buy an HD-DVD player or a Sony "Blu-Ray" disc player. Movies are now being manufactured as high definition discs in both formats but the two formats are not compatible. Both players will play standard DVD's you already have.
In many ways, this is the same kind of format battle we saw between VHS and Beta Max that took place at the beginning of video cassettes. Somebody is going to win. Right now, the HD-DVD players are about half the price of a Sony player. There are also some feature differences.
I was at Wally World and looked at both and for me I liked LCD better but first I will see Samsung DLP and then decide!!