I am going to but a widescreen HDTV. I want to know what I have to get to recieve true HDTV. I heard you have to buy A huge antenna and put it on your roof, is this true? And If I get Dish network or dirctv high definition reciever can I hook an antenna to the reciever, so I would get local HDTV and satelite HDTV on the same box? please help Im completely lost!