You don't seem to have updated your configuration file. You are still using the vesa driver when the higher resolutions probably are possible only with the nvidia driver. Change this:
Code:
Section "Device"
Identifier "VESA Framebuffer"
Driver "vesa"
#VideoRam 4096
# Insert Clocks lines here if appropriate
EndSection
to something like this:
Code:
Section "Device"
Identifier "NvidiaCard"
Driver "nvidia"
EndSection
Also change the references to the "VESA Framebuffer" to "NvidiaCard". You will also have to change the Modes section(s) in order to get 1600x1200 since you haven't got that mode specified at all. Change this:
Code:
Subsection "Display"
Depth 24
Modes "1280x1024" "1024x768" "800x600"
EndSubsection
to this:
Code:
Subsection "Display"
Depth 24
Modes "1600x1200" "1280x1024" "1024x768" "800x600"
EndSubsection
Also, you need to load the "nvidia" kernel module before actually starting X.
modprobe nvidia should take care of that. For more information, refer to the documentation that comes with the nvidia driver.
Håkan