Just a few comments (to all of the messages so far). HD on a disc (Blu-Ray or HD-DVD) will be better than cable or satellite, or SHOULD be anyway. Cable and satellite take the HD picture and still have to compress it a little bit to get all of the channels to fit in their bandwidth. Thus the reason it looks better on a disc than over a cable.
Also, 1080p really is a benefit for the "big guns" as far as screen sizes go. It has been discussed here and elsewhere that this will be a bigger benefit for projection systems with screens near and above 100". That is why you think that 1080p doesn't look any better than 1080i. At 50" 720p and 1080i look almost the same.
I've just started dabling with HD on my 720p front projector at 104" and I am loving it. This is just over the air stuff too, not the "good stuff" like Blu-Ray or HD-DVD...
