How can I increase the Knoppix resolution to 1280x1024? At the boot screen I am typing

Code:
knoppix screen=1280x1024
however Knoppix still switches to 1024x768..

Also, when i use the command dpkg-reconfigure xserver-xorg and I select 1280x1024, still the same 1024x768 resolution is shown.

Should I know the hfreq and vfreq of the monitor to make it work? Cause i think it's a bit of a hassle especially when you are using Knoppix on different PCs with different monitor specifications.

My video card is NVidia GeForce 5700