I'm glad the 'format war' is pretty much over now, possibly most of us can look forward to enjoying the new technology soon, without the worry of it dying out hehe
As far as HD and SD goes, decent HD is loads better than SD, it's true, as said above, CRT's just mask the truth, just blurred things nicely so it looked like a perfect image. Put the two side to side, or flick back to SD and you'll suddenly wonder where all the detail went
As far as sky HD etc goes, older films will look a bit crapper won't they, as they are only upscaled\unconverted(can never remember the right one lol) versions
Also I have 3gb HD video's that look much better than the DVD, but I guess it makes sense as they are the correct resolution for these current tv's and no scaling is required. The difference between DVD and HD seems shocking on an LCD, but a DVD will look better standard on a CRT compared to an LCD tv (obviously discounting upscaling etc)
... obviously the above is part fact\part opinion based