From my 3 months experience with HD dvd, the difference in PQ and Audio quality is really huge, Take the case of The last Samurai, the etching pattern on their clothes are clearlly visible, the grass looks very natural and the color saturation is excellent. For 499 dollars the HD-A1 is a steal. I have 2 DVD players costing 3250 and 1600 US dollars respectively but they cannot keep up with the quality. The picture quality is determined by the weakest link in your system. I dont even care about the demo's in store because I know I can (in most cases) do a better job than they can. I do my own greyscale calibration and to see a video presentation with a uniform d65 color temperature at 20 to 100 IRE is exceptional.
If you will use a 842x480 plasma to display its capability then you are not doing justice to the source. It will look better but not exceptional. Now if you can use a display that can handle 720p or native 1080i then you are in for a treat.
As a general rule, if your display is 60 inch and below then you might see an improvement of 20% but as you go bigger, maybe 100 inch PJ, then the difference will not be suttle anymore.
