When I first went HD, I made the mistake of buying a 32" 4:3 SONY Wega HD. Got the 622 hooked up to it, and sure enough, all Dish HD had black bar top and bottom, and any SD was a full rectangular of black bar. I was so annoyed, that I brought it back in a day. Darn thing weighed a ton, and it was a piece of work just physically returning it. Eventually got a 34" 16x9 XBR CRT, and never looked back. (Even though this baby is even heavier
)
While I can handle left, right black bars (like right now, my son is watching the Grinch from ABC HD - and it has black bars), I could not stand a full rectangle of black wasting the screen.