It needs to be very dark for it to be a nice picture, other wise it will look very washed out. The lumen rating is the judgement behind how bright the projector is, and there for how it will preform in a brighter room. I just hung an in focus projector at my buddies house, same caliber as this, and its nice when the room is dark, other wise it sucks, but I am partial to veiwing 60 sony SXRD LCOS tvs!
Also does this projector display HD? If it has VGA I am guessing it will.