The nVidia 3D drivers at Debian Linux Lenny repositories has bugs preventing it to run over a Xen modified kernel.

Previously you had to apply patches, or manually install newer nVidia drivers.

Now there are a simpler solution to install cleanly Debian way.

You have to install nVidia drivers packaged at Unstable repository section.

To keep your system under manageability control, you have to leverage the APT configuration tools and usa a feature called Pin Packages, mixing repositories with priorities.

You have to edit/create a file /etc/apt/preferences as follows:

Package:  *
Pin:  release a=stable
Pin-Priority:  800

Package:  *
Pin:  release a=testing
Pin-Priority:  101

Package:  *
Pin:  release a=unstable
Pin-Priority:  99

Package:  *
Pin:  release a=experimental
Pin-Priority:  9

Package: *
Pin: release a=lenny-backports
Pin-Priority: 200

Package: nvidia-kernel-common
Pin: release a=unstable
Pin-Priority: 999

Package: nvidia-glx
Pin: release a=unstable
Pin-Priority: 999

Package: nvidia-glx-dev
Pin: release a=unstable
Pin-Priority: 999

Package: nvidia-kernel-source
Pin: release a=unstable
Pin-Priority: 999

Package: nvidia-graphics-drivers
Pin: release a=unstable
Pin-Priority: 999

Package: nvidia-graphics-modules
Pin: release a=unstable
Pin-Priority: 999

Package: nvidia-kernel-2.6-686
Pin: release a=unstable
Pin-Priority: 999

Then modify your /etc/apt/sources.list file to something similar to, including unstable repositories:

deb http://security.debian.org/ lenny/updates main contrib non-free 
# deb file:/var/cache/apt-build/repository/ apt-build main 

deb http://www.debian-multimedia.org/ lenny main 

deb-src ftp://ftp.br.debian.org/debian/ lenny main contrib non-free 
deb ftp://ftp.br.debian.org/debian/ lenny main contrib non-free 

deb ftp://ftp.br.debian.org/debian/ unstable main contrib non-free 

deb http://www.backports.org/debian/ lenny-backports main contrib non-free 

deb http://volatile.debian.org/debian-volatile/ lenny/volatile main contrib non-free 

## tentativa de misturar pacotes de versoes, sendo stable a principal
deb http://security.debian.org/ testing/updates main contrib non-free 

deb-src ftp://ftp.br.debian.org/debian/ unstable main contrib non-free 

deb ftp://ftp.br.debian.org/debian/ testing main contrib non-free 

deb-src ftp://ftp.br.debian.org/debian/ testing main contrib non-free 

After, issue an apt-get update command, as root.

If you already booted the machine running the Xen modified kernel, by now you should be at a command prompt, without a X Window graphical environment.

Then, issue the commands, as root:

module-assistant prepare

module-assistant auto-install nvidia

By now, you will able to test your packaged driver, issuing the command

startx

For sake of consistency, exit the graphical environment and reboot machine, observing any error message.

This time, you should get the graphical login (gdm, kdm, xdm).