What comes to TNT2, I've had one and at Cel 566@850, there was a huge difference between TNT2 and Radeon 64mb.
Radeon is like twice better.
in AH, flying through smoke caused FPS to fall below 10, while Radeon was 40fps and even with whole field smoking, Radeon was keeping +20 fps.
It is at 566mhz, where Radeon and TNT2 comes "closer" in performance.
Now that we have R8500, GF3, GF4.. well, TNT2 is like lada parked aside brand new BMW.