With a 16:9 projector and a 16:9 screen you will have the following:
4:3 material, bars on the sides and most likely light spill, but you can mask it off.
HD broadcasts which is 16:9 (1.78 aspect ratio) perfect fit on the top and sides.
DVD movies 1.85, very close to 1.78 above, you won't noticed the bars on top/bottom as the overscan in the projector/tv will take care of it.
2.35 Cinemascope movies (and other aspect ratio's above 1.85) will have black bars on the top and bottom, and most likely you will see some light spill, if that is what your talking about.
Bottom Line, your always going to have black bars for the wider movies like Star Wars, etc.. with a 16:9 screen and even worse with a 4:3 screen. You'll have less headaches if you match the screen to the projector.
