nVIDIA ForceWare Driver Will Not Install

I am having some serious issues with my system. I have recently tried to revert back to my integrated graphics GPU (GeForce 4 MX) from a GeForce 6200 OC. (The card wasn't performing good). When I first installed the card I had to disable the integrated graphics and uninstall all of my previous drivers. This went smoothly. However, upon trying the revert, I cannot seem to get the system to recognize the GPU and the AGP is disabled. When I go to install my new, updated drivers for the integrated GPU, I get an error message (in the install program) that states something like "cannot find driver device compatible with current hardware." WTF!!! In the Hardware Devices list, I cannot locate the Display Device (which would be the GeForce4 MX) at all. My motherboard sucks because it doesn't allow direct BIOS modification so I can't use most of the information here on the web. I've tried just about everything in my power to get my system to enable a Display Device but I cannot seem to figure this one out. I would really like to see my system back to normal before I upgrade to a 6800GT OC. (and more RAM). If anyone can give or lead me to any information, that would be EXCELLENT! Thanks.