Ubuntu 9.04 + Nvidia FX 5200 PCI + Xorg = unhappy configuration

Ubuntu 9.04 + Nvidia FX 5200 PCI + Xorg = unhappy configuration

I have a Dell Dimension e510 computer, with on-board video (disabled). I also have a Nvidia FX 5200 PCI card that I installed after the fact. I had to do some searching to even get Ubuntu 9.04 to install on this (disable acpi i think). Now I got that running, and the machine is using the nvidia-glx-173 drivers.