Here we go:
That is the Panasonic Vierra 37" Plasma, and as you can see, its an ok size for a room of those dimensions. The 46 is going to fill that bay leaving 5" clearance either side towards the windows, so should fill it nicely.
"If" i ever get it on teh wall, as it sounds as though its been boarded, so, what lies behind? Bloody brick i prey, as these TV's are heavy.