That's exactly what I've said. I've done some heavy research and came up with this:
5x.xx drivers use a lot of performance to increase video quality. The FX serie, for wich these drivers were designed have enough power in them to be able to handle high framerates. For the Ti serie, such power is not avalaible, so the framerates go down a little bit.
UNLIKE ATI, NVIDIA ALLOWS YOU TO DOWNLOAD OLDER DRIVERS,(I've searched the ATI site and were unable to find any drivers for ATI RAGE , but could very easily found drivers for NVIDIA RIVA TNT on NVIDIA's website),like Detonator whatever(3x.xx, 4x.xx), Force Ware whatever(5x.xx), you name it. Actually I could download every driver NVIDIA has ever made. It's not that they don't write them better or that we're talking about incompatibilty issues, it's just that the Force Ware drivers(5x.xx) are optimized for FX cards, as I've explained in this post