Getting xorg to recognise two GPU's

In Ubuntu 8.10, after installation of the nvidia driver, xorg is unable to decide which card to use. To fix this, login in to a terminal, and then type

sudo lspci grep VGA

On my machine this gave the following output:
02:00.0 VGA compatible controller: nVidia Corporation Device 05e2 (rev a1)
04:00.0 VGA compatible controller: nVidia Corporation Device 05e2 (rev a1)

So to get the xserver working, you need to add the following line oin the device section of /etc/X11/xorg.conf:

Section "Device"
Identifier "Configured Video Device"
Busid "PCI:2:0:0"
Driver "nvidia"
EndSection

Then run:

sudo service gdm restart

to get the xserver working as normal.