A little late, but I've got a bit to say here...
...there is a very clear difference between upconversion and true HD. Perhaps if people don't have a good enough TV, then it could be hard to tell.
And then there's some of the idiots who think that just because they buy a device that plays HD formats, that they suddenly "have HD" on their 20 year old TV set. Negatory.
I had an HD-DVD player and an upconverting player, and the difference is phenomenal...