does your laptop graphics card detect your monitor when you open up the graphic settings?  Try to see if it lets you configure the lcd monitor or it might have something to do with hardware scaling, see if poking around your display options lets you play around with the aspect ratio.

Maybe the onboard display of the lcd tv has been set to 4:3 by default? There might be something in the tv menu that lets you play around with it.  By right you shouldn't need to get a special cable to get it to appear in the correct aspect ratio.