I use gnome 2.26.1 + compiz-fusion on my Archlinux box. I wanted to add a second monitor to it. I have nVidia GeFore FX 5200 card and the following drivers
[W@localhost ~]$ pacman -Q | grep nvidia
nvidia-173xx 173.14.18-2
nvidia-173xx-utils 173.14.18-1I connected one monitor through
DVI cable and the second by the
VGA cable. I had no problems setting dual screen using nvidia-settings program (it comes with the above drivers). Below are my settings:
I also attach a photo of my compiz 3D cube on dual monitor screen.
Later I change the monitors to have two, the same one.
It can be noticed, that each monitor "is" on a different site of the 3D cube:-)
I also attach a photo of my compiz 3D cube on dual monitor screen. 
Later I change the monitors to have two, the same one. 
It can be noticed, that each monitor "is" on a different site of the 3D cube:-)