First off, try the simple stuff. modprobe NVdriver as root, and if it prints out any errors, what are they? If they're "symbol not found" or similar, then you've probably installed the wrong NVIDIA_kernel RPM. Download the nv_chooser script off the driver download page and run it; it should tell you which RPM to use. If you don't get errors, continue on to:
What does [ -c /dev/.devfsd ] ; echo $? print? If it prints a 0, you're using devfs; if it prints a 1, you aren't.
If you are using devfs, then change the alias char-major-195 NVdriver line in /etc/modules.conf to alias /dev/nvidia* NVdriver. And get rid of the NVdriver line at the end, that's not even the right syntax for this file.
If you aren't using devfs, then check to see that the /dev/nvidia* devices exist -- ls /dev/nvidia*. If they don't, then you'll have to create them. And if youre not using devfs, the "NVdriver" line is still the wrong syntax for this file; get rid of it.
If you make changes to modules.conf, run depmod -a (as root) to update cache files and stuff, then try loading X (with the nVidia drivers being used).