there will be an upconverter in the transmission path that passes hd progs but upconverts normal sd prodgrams. These sd progs could already be widescreen or 4:3. Someone will have made the decisions on how these 4:3 signals are handled . Crop top and bottom and make them 16:9 or even compromise 14:9 ( narrow black bars at the side ) or leave them as they were made ie 4:3 with wide black bars and obviously the simpsons is left as is. Can't comment on the sd feed as I don't have it on my box HD only