xorg

Make sure you have back-ports repository configured if you want a more recent version of the nvidia drivers which i highly recommend. Also the steps below need to be followed exactly so proper dependencies are met.
This will install kernel headers from stable

Step 1: apt-get install linux-headers-`uname -r`

This will pull in a more recent version of the Nvidia Driver from backports

Step 2: apt-get install -t squeeze-backports nvidia-glx nvidia-xconfig nvidia-kernel-dkms nvidia-settings

Step 3: nvidia-xconfig