well, one thing about making realistic light... while it is remarkable how close to life these programs get these days, they still aren't quite the synthetic equal of real life, so while a single light in a room in real life may light a room adequately, that may not be the case in 3D. In real life, EVERYTHING reflects light in some form or fashion (unless it's utterly and completely black). This light reflecting off walls, objects, etc causes the light to travel through the room... so, keep that in mind.