Well, to reply to that last matter...
Picture quality is determined by a lot of things and resolution is an important part of those.
Most of the modern TV-sets can handle better
horizontal resolutions than necessary for common NTSC or PAL. (As a result you may see a significant improvement already when playing 720- or 1080-lines material on a common TV-set, at 480 vertical lines.)
Of course that will even significantly improve if you go to real 720 lines material on a 720-lines display and again if you step up to 1080 vertical lines. So, in principle, the answer to your question is: yes, 1080 vertical lines (and the accompanying horizontal resolution) are significantly better than 720 vertical lines. The improvement factors (480 -> 720 vs. 720 -> 1080) are the same!
However here are some caveats:
(1) Does the TV-set really display full 1080 resolution?
Many "HD-Ready" TVs do not have 1920 x 1080 screens.
(2) How big is your display and how far from it are you sitting?
If you're sitting relatively far away from a relatively small TV-screen, a 1080-image on your retinas may hardly have a better resolution than the 720-image on the retinas of someone sitting closer to a somewhat bigger screen.
(3) How does the TV-set process the incoming image signal?
Some TV sets (many actually) do not process 1080p signals "properly": they convert it to a lower resolution first and then "upgrade" the image to 1080 vertical lines. (It is said that some other TV-sets do the same for 1080i, but actual info seems missing).
If you're going to buy a projector for HR movies, make sure you buy one that can do *real* 1080i and 1080p stuff. On this forum you will find very positive reviews of buyers of the new Sony Pearl (VPL-VW50), which seems to be just under $5000. I ordered one of these myself, but I didn't receive it yet, so I cannot tell you from own experiences if the're right.
Cees
