the standard resolutions for windows are not widescreen, so you need to force your resolution in to a widescreen resolution, I don't know how to do it off the top of my head but just google "pc to hdtv" and it will give ya tips
Yours is REGZA HD Panel (16:9). 1366 x 768 resolution.
Change your 2nd Screen Resolution to Display Properties 1360 be 768.
right click on your screen.
select 2 display.
slide SCREEN RESOLUTION to 1360 by 768.
Or from the Control Catalyst Center, click DISPLAY NAMAGER.
select number 2 monitor.
select 1360 X 768 on Desktop Area. or select force HDTV Mode to 1280X720 @ 60Hz or 50 Hz depeding on where you from. try other mode fo to get the best resolution for your TV.