FX5200 and 8800GT Video cards DO NOT work in the same system.
I wanted to upgrade my current PCIex16 NVIDIA 8800GT computer with two monitor outs to have a third monitor. I have the monitor sitting here, ready to go, and i ordered a PCI (not PCIe card, which I have no more mobo slots for) FX5200 because the www.nvidia.com site shows Vista drivers for it. I use Vista 32bit.
So I got the card and excitedly installed. Drivers install, BSOD. Crap.
Restarted, fiddled, tried different driver versions, changed video priority in the BIOS, nothing helped. I even tried some modded video cards from some 3rd party sites in the hopes they would magically bypass this problem - nope.
In short, in case you're wanting to install an NVIDIA FX5200 with an NVIDIA 8800GT, it just doesn't work. NVIDIA sadly does not give a shit either, because I can find a few others posting about this online too, with no help from NVIDIA or plans for a future driver.