As Kazic said, make sure you spend the money on component cables. It will make a huge difference. The worst part of having a HDTV is that after you see a good picture (PBS) you can't go back to regular channels. So prepare yourself to watch a lot of documentaries.
Also, most of the network HD channels are very compressed so the pic, though bigger, isn't that much improved. Another year or two...
Don't forget a nice progressive scan DVD player!