Smart move. Nvidia seems to support the open OSes much better than ATI. Even on Windows, I had always found that while ATI cards might perform well, their drivers sucked pretty bad. Nvidia was famous for having some solid, polished drivers.
I use the Nvidia binary driver for my FreeBSD system to get hardware 3D.
Only had one issue recently... apparently with the way things stand now I can't have glx (hardware 3D) and the new "composite" extension in Xorg at the same time.

Hopefully that gets resolved soon. I know composite is quite new and not used much, but still.