help with gateway 19" display (picture included)

Just got a dell 19" display for my macbook.

I want to make it so I can use 1440x900, but every time i do that a big chunk of the screen is cut out, but not when I make it 1360x768, it says it support 1440x900, so what's going on? Am I missing something? can anyone help?

I also want to make it a dual screen if at all possible...


here is what it looks like...

and yes the dock is on the right side, flush with the edge

 

solved the problem....bought a new monitor! neither apple nor gateway could help...awesome