For anyone still awake...
Using tarballs of either 3123 or 4191 rivers got me in the same quandry.
When trying to enable 3d in SaX it said it wouldn't unless I install NVIDIA_GLX...something I had done before trying the tarballs.
That and various checks weren't happy with the kernel module - but the make for that was clean and lsmod showed it in there.
So... I did a YOU and downloaded the Nvidia code from there and let it install. rebooted and when i went into SaX to enable 3D it was already enabled...
So do I try a newer tarball now ? I don't know but I sure can change runlevel, apply the code and reboot back to X quite quickly now....and I know about a few commands I didn't before.
There seems a lot of traffic on these Nvidia drivers so I think I may wait until the issues go away (in 2003....).
Hope all this typing has saved someother poor devil going through the hoops.