These instructions for installing an Nvidia card to use with IMOD may
be helpful.  They were updated in May 2010.  The list of steps assume that you
have already installed Linux with xorg-X11 and its associated drivers.

1. You need to have an appropriate source and header packages corresponding to
the kernel that you are running.  On Fedora/RHEL systems these are
kernel-devel and kernel-headers packages.  You can install them with:
   yum install kernel-devel
   yum install kernel-headers
or by installing the corresponding rpms from your distribution disk, e.g.
   rpm -ivh kernel-devel*.rpm kernel-headers*.rpm

2. Go to the Nvidia web site (http://www.nvidia.com) and go to the driver
download page.  Specify your card type and OS type and use Search to find the
latest stable release drivers.  Download the file, e.g.
NVIDIA-Linux-x86_64-195.30-pkg2.run.  Notice links to the README file, which
you may need to consult.  After you have
installed the drivers, this file is in /usr/share/doc/NVIDIA_GLX-1.0.

3. Switch the screen to console mode (Ctrl-Alt-F1) and log in, or ssh from
another machine.  Bring the machine to runlevel 3 with:
   init 3

4. Go to the location where you have placed your Nvidia install file and
run it as recommended in the instructions, e.g.
 sh NVIDIA-Linux-x86_64-195.30-pkg2.run

Allow it to modify your xorg.conf for you. If the procedure fails, you will
need to research the problems with your version of Linux.

5. Check your /etc/X11/xorg.conf.  Make sure your driver line says "Driver
nvidia".

6. Type startx and see what happens. Success is indicated by a Gnome or KDE
desktop.  Failure is a message saying the X server cannot come up.  A
frequent message is a complaint about no/missing screens.  This really
means that the nvidia driver could not start for one reason or another.
You can examine the start up process in detail by looking in the file
/var/log/Xorg.0.log.  Make sure that the number of bits specified in
the Display line matches up with one of the screens that is declared.

7. Log out of the session started with startx.  Return to runlevel 5 with
  init 5

8. Log in as a normal user.  Assuming IMOD is installed normally, run 3dmodv
on the file yeastpore.mod (available in 
http://bio3d.colorado.edu/imod/files/imod_data.tar.gz):

   3dmodv yeastpore.mod

Start the model spinning by typing Enter and 8 on the numeric keypad.
After 5 seconds or more, type o to get an output of frames/second.
You should probably get at least 200 FPS. If it is a lot slower than this, the
Nvidia drivers and GL libraries may not be installed correctly.

9. Note that you need to reinstall the Nvidia drivers whenever either the
kernel or X is updated to a new version.  Just follow steps 3, 4, and 7.
Or, with recent packages, after the machine is rebooted and fails to start X,
you can enter, e.g.,
init 3
sh NVIDIA-Linux-x86_64-195.30-pkg2.run -as
init 5