Well I noticed that you didn't set the option in xorg.conf which is
Option "NoLogo" "1"
With that said, when you shut down the X server and then restarted it, did you see the nvidia splash screen ?
Also, I am wondering if you played with the following option in the xorg.conf file in your video settings, which is :
If not, try playing with that setting. Valid options for that setting are :
Option "NvAGP" "0"
Option "NvAGP" "1"
Option "NvAGP" "2"
Option "NvAGP" "3"
Only use one at a time
) And just for your knowledge the description of each are :
"0" ... disables AGP support
"1" ... use NVAGP, if possible
"2" ... use AGPGART, if possible
"3" ... try AGPGART; if that fails, try NVAGP
Personally I use 1, but that's what "acceptable" for me. You can play with each setting and see if you see any/no improvement.
But if your not hitting the splash screen everything I said after that point is irrelevant cause it would appear to me that the driver isn't loading, cause like I said if you didn't set the option not to display it, it should be displaying.
Also, just out of curiousity, what kernel version, and what nvidia driver version are you using.
Oh, one more thing I thought about, that affects some users of nvidia cards, is not have dma enabled on your harddrive. So you also may wanna check that too. Crash course to check this is as follows.
Under the assumption your first drive is /dev/hda you issue this command as root :
hdparm /dev/hda | grep dma
your result should be :
it is set to one, you will just enable it by typing (again as root):
hdparm -d1 /dev/hda
Again, if it states using_dma is 1, then your fine in that department, but its worth checking.