I currently have my Xbox 360 Elite displayed on a PT-AX200U Panasonic Home Theater Projector. This thing is a light cannon. I have a considerable amount of light entering my room and this thing gets so bright it still makes me squint from time to time. It has a gaming mode that makes games look better (enhanced shadow detail) and reduces the delay to get the gameplay image to the screen (when I die playing Halo 3 online, it really is because I suck, not just because the image on my display is lagging behind the action).
This thing could easily do well on a screen up to 200 inches. I have mine set up on a 92 inch screen and with all those extra lumens on that size a screen, it literally makes my eyes hurt sometimes because it is so bright. I got my projector and screen for less than $1800 total and that is for an image more than three times the size of a low end $3000 50 inch plasma!!!
I have noticed that people rarely consider projectors for their television/movie/gaming display, but the reasons are usually not based in fact. You should seriously check this out prior to making a decision on another display.
Here are a couple of review sites for this projector:Projector CentralProjector Reviews