You have an HDTV (going by your sig) which are typically limited to 1368 x 768 or something close to that...
I have a 24" @ 1920 x 1200...
You bought an HDTV, not a PC monitor... although they can be used for both purposes, PC monitors tend to have higher resolutions at lower screen-sizes.
Small TV's don't make the best of monitors since they are limited in resolution - unless it's a 1080P set. It's hard to find a TV 32" and smaller that's 1080P.