First of all, the there is no TNT Ultra, it is the TNT 2 Ultra, its the TNT 2 chipset but with faster clocked ram and some other things like I think an onboard cooling fan.
The ATI Rage Fury 32 bites. G400 sounds good and looks good but I'm still unsure about Matrox cuz of their past with vid cards for gamers and business dudes.
The GEForce is 30% - 40% faster than the TNT 2 Ultra. I know that as a fact cuz many magazines have benchmarked it and tested it among games.
About your question to what card is good for D3D and/or OpenGL, I would say, get the TNT 2 ULTRA and when Transform & Lighting supported games come out, there will be new generations of cards out. But I am warning you, the TNT 2 ULTRA does go on its knees in UT, thats what I heard though. So if u buy the TNT 2 ULTRA or TNT 2 and u come here yelling at me, don't yell at me...look at other posts on this messageboard about the TNT 2 Ultra or not w/ UT.
Good Luck, Hope I cleared some vague stuff...