Not overly really. 3DS max since 2009 iirc has had viewport acceleration with Geforce cards starting with the 8800GT. It wouldn't hurt to go for a professional card, but I would find it hard to justify. Now regarding CUDA enabled rendering engines (not sure 3DS Max can do this yet) faster the card the better, however VRAM is a massive pain in the arse and can limit rendering jobs hugely so go careful if you think that's the path you want to follow. Also the CUDA standard keeps changing and you could find your GPU's unsupported in later released, like I've found with my GTX280 and Blender 2.66 (Cycles engine). For that sort of cash, I would build a solid CPU based rendering rig, it can weather software changes far better than CUDA or OpenCL rendering methods. As for teaching have you considered a projector to show students what you're doing, rather than the sit along side method which isn't hugely effective.
When im teaching i dont touch the computer i just look over the students shoulder. i mirror the desktop when i need to do demos so they can see exactly what im doing. i did consider a projector but its a bit of a frivolity when im teaching one on one. Thanks for all the info all, really appreciate the help. im currently in deep negotiations with the mrs about moving my study into another room so i will have space for a small render farm rather than spending all that on a single system. I'm pitching it as she will be able to have a walk in wardrobe out of the old study. so far so good.
Win! I've just had bought for me at work a system with a i7 4930K, 32Gb Ram, and a Quadro K4000 for this years Solidworks rendering. I would have saved and not got the Quadro, but they insisted on certified hardware. Can't wait for it to turn up this week coming!
