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
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