On a computer with Debian Wheezy, 64 Bit Gnome in the classic view is installed. Gnome 3 can not be used.
Install the driver for NVIDIA.
Deinstall the acutal used driver
# apt-get purge xserver-xorg-video-nouveau
Install the correct Linux-Header
# apt-get install linux-headers-`uname -r`
Install the new driver
# apt-get install nvidia-kernel-dkms nvidia-glx build-essential nvidia-settings nvidia-xconfig nvidia-glx-ia32
Create /etc/X11/xorg.conf
# nvidia-xconfig -o /etc/X11/xorg.conf
Check it
# nvidia-xconfig -o /etc/X11/xorg.conf
Content
# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig: version 304.48 (pbuilder@cake) Wed Sep 12 10:54:51 UTC 2012
Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0"
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
EndSection
Section "Files"
EndSection
Section "InputDevice"
# generated from default
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/psaux"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection
Section "InputDevice"
# generated from default
Identifier "Keyboard0"
Driver "kbd"
EndSection
Section "Monitor"
Identifier "Monitor0"
VendorName "Unknown"
ModelName "Unknown"
HorizSync 28.0 - 33.0
VertRefresh 43.0 - 72.0
Option "DPMS"
EndSection
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
EndSection< br />
Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Depth 24
EndSubSection
EndSection
Rebbot your system to choose the appropriate view.
Source: http://wiki.debianforum.de/Unfreie_Grafiktreiber_f%C3%BCr_NVIDIA