First of all, use the real nVidia driver, from
then, as root:
follow the prompts, let the installer fix up your config files, wait until it is all done, do:
apt-get install kdm
make sure nvidia is the driver
uncheck the glx and dri modules
as long as you are here, make sure your monitor sync ranges are correct. Look on the specs for the monitor and find the horizontal and vertical sync ranges. Select advanced, when you get to monitor, and enter the sync ranges.
Finish the whole xserver configuration.
At the prompt:
The nvidia screen should show. Then X will work.