Re: ERROR : unable to determine the nvidia kernel module filename
If you do have the Nvidia driver now, you have to tell X to use it. You do this by editing the file /etc/X11/XF86Config. In the Device section, change the line starting with "Driver" into 'Driver "nvidia"'. In the README that came with the installer there is a section explaining all this -- you will have to make a couple of changes, like removing the lines about loading dri and GLcore.
If you have done all that, you should be able to get X up and running with "startx", for instance.
By the way, we have now apparently succesfully *downgraded* your kernel. Assuming you will want to upgrade sometime, you have to do the following:
if you install a new kernel using rpm, you have to *upgrade* the kernel, not install it. The rpm install option means you will lose your old kernel. So, from the command prompt you would do:
# rpm -Uh kernel-<whatever>.rpm
Then, you will have to re-install the Nvidia driver (the easiest is to do this after succesfully booting your new kernel, but see the README for more info on how to it all at once). This should be simple, just run the installer script once more. If you have a working configuration by then, that's all -- no need to fiddle with XF86Config.