Oh! Your speaking of the driver optimizations that nVidia made on their drivers, (I believe). ATI has/is doing the same thing. ATI is backing, (driver optimization if not monetarily as well), Half-Life 2. And nVidia has always favored Quake, UT, and will be backing the new Doom. It's almost the same as the preferences of processors, AMD or Intel, it's all in what you prefer.
Personally, I have always loved UT and hence I prefer nVidia. But ATI has really left a few bad tastes in my mouth over their driver compatibility with graphic arts programs in the past.
Currently I have a 128mb nVidia 5900 ultra and love it! If the real tests come in showing a 2x frame rate boost with AA as shown in the preview tests, I will lay down the $$ to get it.
I only hope that someone decides to bring one of these beasties to the Mac platform!