I use Maya and the difference between a 5870 and a Quadro 4000 can be the difference between 5fps and 300fps in some high poly scenes. Not sure if it translates to C4D the same way.
You should mention some context with that, as you previously stated it was under Windows 7. Google turned up a lot of complaints with the 5870 in general under Windows with things like Maya. NVidia's cards in general seem popular. In general the Quadros seemed to come out on top overall especially when it came to bugs/stability, but I'd avoid any abandoned cards.
The Quadro 4600 is ancient. It's like a grandfather to the Quadro 5000 if I recall correctly. I don't know how the OP would fair getting that to work under Lion. The price doesn't seem too great either. Anyway wasn't that from 2006ish?
With the Quadro 2000, I haven't seen any tests of that one under OSX. That would be an issue. If he's going for a quadro under OSX, the Quadro 4000 Mac edition at $700-750ish would probably be the way to go. Unfortunately it doesn't have some features I'd like at that price like OpenCL support and 10 bit displayport functions (mostly an
problem).
Wow that's quite a difference, and confirms what I have read elsewhere for Maya.
Out of interest is that running Maya on OS X or Windows 7?
The reason I ask is that OpenGL support is somewhat problematic on OS X.
The CINEBENCH 11.5 GPU results I have seen suggest that the performance would double from a score of around 30FPS to 60FPS. The biggest advantage would be with fluid simulation plug-ins that use CUDA.
Strausd writes a lot of (genuinely) interesting stuff, but I think he's annoyed with Apple right now on graphics cards (not that I blame him). He mentioned this in another thread too. It was under Windows 7. If you do a search, the 5870 is terrible within maya under Windows 7. Now that doesn't mean that the Quadro 4000 isn't superior under Windows 7 isn't still superior to the 5870 under OSX. It's just that discussions over the AMD thing are all over the net and Autodesk even tests a 5870 machine under OSX as it's one of the more common configurations. They do not certify the Mac Pro under Windows 7.
OpenGL seems to be poorly implemented since SL or so. As for Maxon, that's a separate issue. There are different things to it. If it was between two cards, I'd usually pick fewer annoying bugs over fastest possible speed (meaning typically workstation drivers).