Have you tried this forum? :
http://www.avsforum.com/avs-vb/
Maybe they got some answers?
My opinion:
If your watching regular 480i through a bigscreen tv after your all used to HD resolution, then of course the 480i is going to look crappy, especially since it is also compressed mpeg digital format. When the screen size gets that big with mpeg, you can start to see artifacts of compression on many lower quality channels that didn't buy enough bandwidth.
Don't worry though, someday, all channels will be in HD 720p or 1080p because by then, all Americans will have bigscreens, and HD will have to become the new std in order for us to tolerate the picture