System Settings vs YaST

I am a newbie to linux but keen to get it working properly with my hardware. I have suse 11.1 installed and it has detected my monitor and graphics card (Acer AL1916W and NVidia Geforce 6100).
Looking in YaST the monitor settings all appear correct (1440 x 900 16:10 etc). However the screen image looks more like a 4:3 aspect ratio resolution stretched out sideways.

Accessing the system settings > display > size and rotation section reveals a default setting of 1152 x 864 and in the drop down all the alternatives are of a similar aspect ratio i.e. not widescreen.
Can anyone explain to me why the YaST and System Settings appear unrelated? and how this might be resolved?