Aye, it is supported. I was surprised myself when I found that the drivers support my ancient Nvidia 8meg Vanta! What's amazing is that all the roms I've tried run beautifully and lag-less. It also has to do heavily on the fact that this particular system has a fairly good processor. n64's graphics requirements are highly overrated. Personally I love uber low poly modeled games, as it appears to me as more artistic in quality. Much of the cool looking stuff is based on excellently painted textures on flat surfaces.
Anyways, since the emulators are "emulating", the majority of the resources used are from the processor, as that is what is doing all the emulating. This alows me to poke fun at my friend because his system that can run Morrowind and mine can't, cannot play SSB without lag and mine can. I gave him the card I was planning to use in my new 1337 server (32meg Radeon 7k) and threw my old Nvidia Vanta 8meg into my machine as a makeshift replacement.
Unfortunately I was unable to run both my Vanta and my ultra cool Voodoo 3500 simaltaneously. For some reason the PCI voodoo overrides the Vanta's AGP interface. When Windows boots and I try switching my monitor plug between cards, I just get a garbled screen.
Sad to say that I had to sacrifice it for the OpenGL-ness and uber cool always-up-to-date Nvidia drivers. Oh well.