Download nVidias latest driver from: http://www.nvidia.de:

We assume you download it to /tmp.

cd /tmp
wget http://de.download.nvidia.com/XFree86/Linux-x86/173.08/NVIDIA-Linux-x86-173.08-pkg1.run

By the time you download, you might expect a different version.

Leave your GUI and go to a real command line:

/etc/init.d/gdm stop
cd /tmp
sh NVIDIA-Linux-x86-173.08-pkg1.run

Finally run:

nvidia-xconfig -add-argb-glx-visuals -d 24 -composite -allow-glx-with-composite

and follow the instructions.

After a reboot, you will see nVidias background picture prior your login windo