A little of both actually. The chipset hasn't seen an update since shortly after Vista came out, so if the Vista drivers won't work then it has to rely on whatever support maybe built into Windows 7. It also doesn't help that the video card is AGP as it requires a working AGP driver (part of the chipset) for its driver to install and work properly. Probably find that if it was the PCI-E version of the 6200, you wouldn't be having the problems with it.
Also considering the cards age and that it is AGP I wouldn't go for any of the newer Nvidia drivers for it, as they are all more geared towards the current generation or two of cards. Instead go for one of the older ones from the 197.xx or 196.xx series of drivers, NVIDIA Driver Downloads - Advanced Search
Just locate your card from the dropdowns, select the OS and hit Select.