About to buy a 50" Toshiba Rear Projection set and am starting to get doubts that I have enough room for it. Not literally the set itself, but am I going to be able to sit far enough back to get a crisp picture. At the moment I'm about two metres back and I like my sofa where it is. If I'm sitting that close to a 50" screen is the picture going to be sharp enough? How far back do you all sit to get the most of your big screens?