Why do my SD stations on look so much worse then I remember seeing them on my old SD TV. HD stations look great on my HDTV (768p native resolution on my 50in plasma HDTV), but the SD stations look worse then ever?

1. Why do SD TV channels look so bad on HDTV's?

2. Also, if i had a 1080p TV and my source was 1080i, just to clarify, my TV would typically upscale the image to 1080p. Is that correct? I know it depends on the model of TV but is that how it should work, similiar to an upscaling DVD player?

3. Lastly, if i had a 1080p 50in plasma and i'm seated 11 feet from the TV would there be a noticeale difference between the 1080p TV and a set which does 768p or 1080i at that veiwing distance and screen size?


Please advise. Thanks