I got the GeForce 7600GT (256 MB, 128 bit, GPU 560 Mhz).

Works great The VPU errors and freezes are gone. I don't have to reboot between changing planes. I cranked up pano scenery to photo quality. It's a good card for FS One. Apparently the ATI x850 is faster, but I couldn't get that one.

I'm using the "ms flight sim 2004" set up profile in the NVidia set up.

So in conclusion, a low end card like 9250 is very usable with some tweaking, but a little inconveniant. It's good enough to allow you to practice the thumbs (while still having very good visual realism) until you get a better card.

edit: I forgot to mention in my conclusion, that having minimum RAM does not seem to be a big issue at all. I have only 512 MB ram and I see no reason to upgrade it. FS One is running great on my hardware now; perfectly. I have dual channel ram which might help. So in particular if your system ram is 512 MB dual channel, try it for a while before spending anything on ram upgrade... you might not need to upgrade.