I am using the Alum. Macbook (not pro), and I would like to use my Hanns G monitor with 1680 x 1050 resolution but it only shows 1920 x 1080. I'm connecting it with a VGA cable any help?

22-inch Widescreen LCD display
16:10 aspect ratio
1680 x 1050 resolution
1000:1 contrast ratio
Component video through the DVI port with the included DVI-I to YPbPr adapter

15-pin VGA