Thank you all for the fast reply on my problem. I finally figured it out when I looked at the system log. The NVdriver kernel module was complaining that an IRQ was not set for the VGA adapter. So, I rebooted, enabled the IRQ for my video adapter in the BIOS, and X windows launched right up. The 3D acceleration is working great. I installed and fired up Quake III: Arena, and was getting as good a results as I can expect from my PII 400.
Thanks again, Ben Diedrich P.S.: Blame those long lines in my initial message on Web Pine. I didn't realize they hadn't implemented line-wrapping like the original.