I have a BenQ GW2400 and a Geforce FX5200. I run Ubuntu Karmic 9.10, and have the newest proprietary Nvidia driver installed. The GW2400 supports 1920x1200, but I can only select 1600x1200 from the nvidia x server program. Does anyone know how to enable higher resolutions? I've read something about adding custom modelines in /etc/X11/xorg.conf and so on, but I don't know if that applies to Karmic.
I tried all of the approaches in the answers below, with no success. Everything got sorted out as soon as I upgraded to Ubuntu 10.04 (even fixed my half-broken WLAN connection). Anyways, thanks for answering guys :)