Yes, I tried NvAGP set equal to 0, 1, 2, and 3. I ran
startx -- -logverbose 5
each time to confirm that X was interpreting this correctly. It was. Still no FSAA in FlightGear.
This system is completely stable with the new 1.0-3123 drivers. But no FSAA no matter what I try!
I wish there were a log file that shows how the NVIDIA driver is interpreting the environment variables.