The same happends to me :S
I have an 8200 Dell Inspiron Laptop with the nVidia GeForce 4 440 Go and a 1600x1200 display.
The kernel module seems to work and so does the X server... but no output. If I use the option:
Option "ConnectedMonitor" "DFP"
My display begins showing something... but the problem is something weird. Just in case it was a matter of refresh frequency I explicitely set everything with the data I got from fbset. But the same happends...
I have tried both with kernel 2.4.18 and 2.4.19, using and not using frame buffer, and changing a lot of options in the nvidia driver... but nothing works.