From where are you trying to increase the resolution?
Try increasing the resolution from the nvidia display settings which would have got installed when you've have installed your graphics card driver.
Because if you are trying to increase the resolution from the hardware->screen resolution, then it would only show the default supported resolutions!
And its worth mentioning that you should change the resolution as root! or else whenever the next time you restart your system the resolution will get reverted to default, and that is 1024*768 in you case!
Last edited by fireblade_spark; 12-15-2007 at 02:59 PM.