Well, I had a FX5200 for a short time. I was able to play Nexuiz 1.x at 16bpp at 1024x768 with "okay" framerates.
However, it's really important to have a recent driver. With newer drivers Doom3 is on the edge of being "playable" on my FX5200 - nVidia seems to have optimized the crap out it.
Whatever claims to be a "Windows standard driver" for sure is crap - those drivers don't care for OpenGL at all. It's really necessary to install a fresh driver from nvidia.com.