Does it matter who is a fanboy?
Lets review some simple facts:
ATI have hardware that uses Dx11, namely the 5xxx series. It is cheap and relatively fast. It introduced a built in multi displays support, they named it Eyefinity.
Nvidia is new Fermi series will also support Dx11, bulti multi displays and should be faster than all existing cards, plus PhysX and 3D. Unfortunately, it will be expensive and it is not out yet.
Some of the extra cost on Nvidia's video card went to TWIMTBP, a program that offers aid to game developers. ATI also have a program like that, but in a much smaller size.
ATI has tried to engineer their video card to support DirectX, openCL, and openGL. The only innovative about the design is its naming technology.
Nvidia also support DirectX, openCL/GL, plus CUDA, physX, and 3D vision. The idea of 3D is not new, but the 3D vision glasses is.
So Nvidia's video card is more expensive simply because it have some more features. If features that are backed only by Nvidia is not your cup of tea, then get an ATI video card.
If you ain't rich, or willing to spend money on gaming, that ATI is the way to go. 60Hz LCD are cheap, and it is a scalable option. Otherwise, Nvidia is the way to go. SLI + one 120Hz + 3D vision glasses is great, Tri SLI + 3x 56" 120hz projectors + 3D vision glasses is epic. When you are there, 7.1 sound system is more or less a requirement. Don't go cheap on the sound card please. That is why blue rays are for. And do not forget to have several SSDs at raid 0, perfect for gaming or converting Vids. Yes, the cost of changing a bulb = a high end ATI card. So what? Only ATI claims that new techs are cheap, while others know that nothing new is cheap.
I will repeat myself, money is never a problem to me. My problem is, I don't have money.