Hi
 
I had the same problem with my Laptop, i managed it, by adding the resolution to the X11 config file. 
open the xorg.conf in a texteditor as root. 
sudo gedit /etc/X11/xorg.conf 
Now look for the section "Screen", i guess the list of resolutions will catch your eyes, you can't miss it.
Now easily add the Resolution you need. This may look like this.
 Code:
 	SubSection "Display"
		Depth	24
		Modes		"1280x800"	"1024x768"	"800x600"	"640x480"
	EndSubSection
 Now execute the 
nvidia-settings, switch to the "X Server Display Configuraion" panel, choose your new resolution and confirm by pressing Apply. 
now have a lot of fun 
 
  
Regards
Sponge