Thanks for your responses! Terrific info which I will put to use.
One other question which you might help me with. I have a Hitachi 53" HDTV and my concern is the placement of my center speaker. It is an Infinity weighing approx. 8 lbs. The only place I have to place it is on top of the the TV. Is that OK? Although it is "shielded" will it interfere with the picture? Will the weight eventually affect the structure stability of the TV?

Thanks again for your help.