Cannot get Nvidia PCI card to work

So I have this computer that I've installed Ubuntu on, everything seems ok except I'm having one problem. The computer has onboard video. Ubuntu works with this, but it is rather poor in doing even the simplest of things (even simple web browsing). I have a dinky GeForce2 mx400 in there, so it would be better than on-board, but it is PCI.

The deal is, I have to set which video adapter is default in the bios. So if I set it to AGP, it uses the onboard video. If I set it to PCI, it uses the geforce card. When using the geforce, it will go through the boot up sequence, show the Ubuntu logo with loading bar, fill the loading bar, then go to a completely black screen (whereas if I switched to AGP and used on-board, I'd get the login screen). Pressing ctrl-alt-f1 does nothing with the geforce, whereas it goes straight to console with the on-board.

I've tried the instructions located here https://help.ubuntu.com/community/BinaryDriverHowto/Nvidia but I have to do all of those steps with the onboard card. And when I switch back to the PCI geforce, I get the same black screen after the loadbar finishes.

Any suggestions?