It's bigger than your comfortable field of vision. You'd have to actually move your eyes to see other parts of the screen comfortably. You'd be more comfortable with a 50", as I think that's the smallest panasonic makes for those plasmas, and even then it's still a bit large. I'd recommend moving your couch or viewing seat back another 2 feet if possible, it will feel much more comfortable.
If you can, go to a store and just try looking at a tv the size you're thinking of from said distance. If you feel comfortable with it, go for that size and try amazon for a good deal.