I think I figured it out.
First, I had to use my Ubuntu installation CD, and chose "Try Ubuntu".
Next I logged into a terminal session, and have to remount my system partition (ie: /dev/sda1 is where I installed Ubuntu).
sudo mount /dev/sda1 /mnt
sudo mount --bind /dev /mnt/dev
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys
sudo chroot /mnt
This mounts everything I need to run apt-get against my hard drive, rather than the non-persistent Ubuntu running in RAM.
Now I just have to clobber Nvidia drivers, so I can get my system booting again.
# Remove existing drivers
sudo apt-get remove nvidia*
sudo apt-get purge nvidia*
sudo apt-get clean
sudo apt-get autoclean
# Handle any errors to due incomplete apt-get operations
sudo dpkg --configure -a
sudo apt-get update
sudo apt-get upgrade
# Remove xorg/X11/XFree86 references to graphics drivers
sudo rm /etc/X11/xorg.conf
sudo apt-get install ubuntu-desktop
# Clean up and unmount everything
sudo umount /mnt/sys
sudo umount /mnt/proc
sudo umount /mnt/dev
sudo umount /mnt
Now, I will NOT re-install the drivers just yet. Reboot the system, and eject the liveCD. I am now able to log into my existing Ubuntu installation.
Now, go into Jockey (ie: The "Additional Drivers" program, also /usr/bin/jockey-gtk), and see if any Nvidia drivers are "Active". De-activate them with the "De-activate" button, and reboot. Check if any new nvidia driver has been automatically activated. If so, de-activate it, and reboot again. Repeat until jockey no longer automatically activates any nvidia drivers at all.
Now, install the nvidia drivers we want:
sudo apt-get install nvidia-current
sudo apt-get install nvidia-common
sudo apt-get install nvidia-304
Now reboot the system. When you start jockey next, it should default to nvidia-304, and you're set.