Nvidia problem

[Alcott80]

Hi.
I am new on Linux: i have installed Kubuntu 11.10, but I have video problems :(

In the web, I found this commands to update video driver (Nvidia GeForce 7600GT):
sudo apt-get --purge remove xserver-xorg-video-nouveau
K-menu -> Applications -> System -> Additional Drivers and I have installed Current Version "Recomanded"

In K-menu -> Applications -> System -> NVIDIA X SERVER SETTINGS, my NVIDIA Driver Version is 280.13.

But I have system freeze, this screen on startup (pre-login):
http://imageshack.us/photo/my-images/207/caricamentoprimalogin.jpg/

and this screen with CTRL+ALT+F2:
http://imageshack.us/photo/my-images/220/altctrlf1.jpg/

Any idea? Thanks!