Knoppix 511 and screen resolutions

[nnigam]

My laptop which can display upto 1600x1200 only comes up in 1024x768. When I change the display to higher resolution from the display settings in control center | display, I can select upto 1600x1200. However the image comes up tiled instead of streatched to fill the screen, so I end up with multiple images of my desktop. Any way to make this come correctly with the screen streatchec out to fill the resolution?

Thanks
Neeraj