Low-End NVIDIA/AMD GPU Comparison On Open-Source Drivers
With Reaction Quake 3, the tables change again. This time around, the top performers for this open-source game are the Radeon HD 4670 and Radeon HD 6570. On the NVIDIA side, the GeForce 9500GT was faster than the GeForce 9600GSO due to the broken re-clocking on the higher-end GPU.
At least Smokin Guns' isn't too demanding on the graphics cards with the open-source drivers, aside from the Radeon HD 6450 that really isn't good for more than running a compositing window manager on the Linux desktop.
The Warsow performance was okay on the open-source drivers if you're fine with running at a resolution of just 1280 x 1024.