Need help with home theater set-up....

Here is a floor plan of the front part of my upstairs that I plan to turn into a theater area. in the lower left corner is where i plan to place my "home theater" I just need some insight on where i should mount future 58" plasma. I get a lot of afternoon sunlight from the large window but I plan to replace the current curtains with blackout ones. I also will eventually go with a 5.1 set-up.
WALL A = 12ft
WALL B = 11ft

So my question is if you had this layout would you place the plasma on Wall A or Wall B? Or in the corner?



Here are actual pictures of the area




Large Window

Thanks for the help. AVS has been a great info site for me.

So place it on Wall B then, is that what you are suggesting or placing it literally right next to the fireplace?

I was thinking Wall B as well. Guess I'll reconfigure it tomorrow morning to see if i like having the couch the other way.