The system that I doing this on is an old Pentium 4 with an nVidia FX5500 graphics card in it plugged into an old CRT television via the RCA port. After downloading the Intel-nVidia iso from xbmc.org and putting it on a USB stick I installed it using just the default settings.
After the install I found that the GUI wouldn’t load due to installed drivers not having the extensions for OpenGL 2.1. As my card is too old for the regular nvidia-current drivers from the repository, the experimental drivers need to be installed and configured through the terminal. The latest (ie. experimental) drivers are also needed to run the Steam for Linux client.
So switching to one of the terminal sessions (Ctrl+Alt+F1) and logging in enabled me to run the following commands to install the nVidia drivers in the Ubuntu repository.
sudo apt-get install nvidia-experimental-310 nvidia-settings-experimental-310 sudo nvidia-xconfig
followed by an apt-get install update apt-get install upgrade to ensure that everything else was up to date.
However, I then discovered that my card was too old to use the 310 driver so after a quick purge of all the nvidia modules I let the repository pick the correct driver and reinitialised the gui. Using the software sources app I was able to select the the nVidia driver available for my card, which as it turns out does not have the OpenGL extensions that the latest version of XBMC requires.
Unfortunately this leaves me in the position of having to use a newer card. But the spare one I have doesn’t have an RCA AV output, meaning that I can’t connect it to the television that I intended to use with XBMC. The driver version also means that I won’t be able to install Steam Big Picture mode either.
So I’m stuck with trying to find a relatively new video card that has an RCA AV out or buying a newer TV. I suspect my chances are better with getting hold of a newer TV.
So I remembered that my main desktop computer had a newer video card with an s-video out and came with a s-video/RCA cable. So I’ve upgraded my main desktop and can use the card for the XBMC box, but will have to wait for the current refresh at work to complete to get a motherboard with PCI-E instead of AGP.