check out
avs forum and look in the "Display Devices" category.
My recommendation is to get a digital projector. [censored] 57 inches, how about an 80-100" diagonal? No screen required if you have a light colored wall. Way cheaper than plasma, but looks as good (great color and *very* clear)...and *HUGE*.
The room will need to have blinds for daytime, but you will be watching tv that is five feet high, seven feet across.
Don't bother with rear projection.