Video not full size of screen

Hi
I just got a Zotac AD04 for Christmas. I have XBMC installed it seems to running fine but the picture does not take up the full size of the 47 inch TV. There is at least a 2 inch black frame all around the video. Is there a way to fix this? I was previously using my laptop to run xbmc and it was working fine no black frame. Any help would be greatly appreciated.

Thanks