I havent had a chance yet to test the 16mb or 32mb ATI Rage 128's, but they "supposedly" support Alpha Blending, according to ATI's website.
Those two do work like a charm for UI1, but only Nvidia has "real" corporate proprietary Linux drivers, hence all the others run on the reverse engineered open source variants that is available, and none of them will support 3d or alpha blending (to my understanding).
Fiire does not use an Nvidia, but they bough a proprietary driver for their sollution.
I am sure I will be corrected if I am wrong, but that is why everyone is suggesting Nvidia solutions, and frankly that is how you can possibly push other manufacturers into supplying Linux drivers. Vote with your wallet?