Since there us a defect in my laptop screen, I am using an external Dell 1600x1000 monitor. Windows was recognizing the native resolution correctly. But when I installed Ubuntu 10.10, I get only up to 1024x768 in the Monitor preferences. I had a look at this and tried to add resolution by running
xrandr --addmode VGA 1600×1000
but I am getting the error
xrandr: cannot find output "VGA"
What is the way out.