Nordichardware has interviewed 3DHQ on their continued driver support for 3DFX graphicboards.
Performance-wise, a Voodoo5 should be able to run today's games at 40fps. Drivers themselves can only probably add another 5% to the raw performance of the cards, but don't mistake that with games gaining speed from the eradication of incompatibilities. Games that have driver issues with Voodoo cards could gain far more performance increases with the removal of performance- decreasing bugs.