> is there really that much high definition content to watch?
> On minuscle hobby computers like ours?

I think that the amount of HD content out there is barely dependent on the kind of computers we use ;-) To get an idea, go to Youtube, search for a random term and compare the total number of results you get with the number of results you get after applying the HD filter in the search options.

> techcnically impossible in the end...

HD at 720p resolution is possible on the faster G4 based systems we have today. HD at 1080p resolution is said to be possible on the even faster G5 based systems we'll hopefully get some day.