i have a 53"hatchi ultravision rear projection tv. i upgraded the box to a comcast dvr box because friday my 50" pioneer elite comes. i was having trouble with the reception until i took the coupling out that the last tech put between two cables. now the picture is great, not hi def but still great. now i am also getting the hi def channels that i didn't with the other box. i assumed the other box was the same as this one just without the dvr. would the box be different? would the coupling cause the hi def signal to drop? is it normal for a "std def" tv to be able to recieve hi def channels?