geeforce

I have a Benq e2200 hd monitor running on a geeforce 8600 gt card.. it is conected with a dvi to vga adapter. My problem is that windows 7 seems to think i have a 4:3 monitor, because I can only choose from 4:3 resolutions. The highest resolution I can choose is the 1600 * 1200, when the highest...