I got a new blu-ray player and I can pick 16:9 wide or 16:9 pillarbox for the TV. The BDX2500 defaulted to 16:9 pillarbox and that is where I left. But what is the difference, and what should it be set to? Why would you need pillarboxes on 16:9? Is that for playing 4:3 DVD's and not stretching it out? I have a Panasonic S1 plasma.