3) Login as root, enter "init 3" to go to single-user mode. Enter "modprobe nvidia" to load the nvidia-module.
4) Finally, enter "cp -a /dev/nvidia* /etc/udev/devices/" to fix the boot problem.
5) Now just enter "init 5" and you're back in business.
This solved my problem and now it boots fine. Maybe my experience will help others too?
A couple of points. init 3 isn't single user mode. It's standard multi-user mode, non-graphical log in. You could achive the same result by either changing the default runlevel in /etc/inittab, or adding a '3' to the end of the boot parameters at boot time interactively or thru editing /boot/grub.conf.
Secondly, I have a similar config, though 32 bit. I would be curious to see if you could logout and back in several times after doing the above. I can get the system to work (mostly) the first time I start X with 6629 drivers, but subsequent startups cause the system to hang hard. I am reasonably sure it's related to the 2.6 kernel, but it would be interesting to know if the same behaviour occurred on a 64 bit system.