The GeForce 3 support is included in the kernel update.
Unfortunately, the updates are at an end, so you're not likely to ever see GeForce 4/FX support etc.
Also, out of courtesy, if you download the updates from amithlon.net you should probably drop Bernie a thank you mail and explain where you got your Amithlon from and when. He won't come after you if he doesn't like what you tell him, but he likes to know these things.