Using my SAMSUNG lcd TV as an external dual monitor for my HP laptop. Everything is working fine except the screen is off-center. It is shifted to the right where a black bar is on the left and it cuts off about an inch of the screen on this right.
I think this can be caused if your PC/laptop sends out a signal with slightly different frequencies. My Samsung TV does exactly the same during POST (when the PC is booting) but when it gets into Windows everything appears correctly.
Have you set the laptop's output to the native resolution of your TV? Check to see what happens if you change resolutions and/or refresh rates. Also, depending on what graphics cars the laptop has you might have options in moving the image to the left/right/top/bottom using the graphics' card software.