Thanks Alan. The TV is actually 1080i. So, it sounds like I have the cable box set right: 16X9 and 1080i. On the distances from the TV to the couch, sounds like I'll be o.k. as I have about 14.5 feet to play with.
I am not happy about the TV being above the fireplace. What I was trying to avoid by using that configuration was having the back of the couch too close to the fireplace, as the only other option is to move the TV to the opposite wall of the fireplace (and thus have the couch "in front of" the fireplace). However, it sounds like I can have the couch much closer to the TV then I had planned. If I put the couch at about 8-9' from the 1080i 10", that will leave 5-6' between the couch and the fireplace. Having that setup actually is much better for a lot of reasons.
I'm so glad I posted my questions!
