Not enough grunt? I guess that depends on what he's rendering
A £600 machine can make a
very good machine for 3DMax use - certainly with the Quad and plenty of memory as you said, which would fit within budget by the looks of it
Its no where near as simple as looking at the FLOPS of each card - That is over simplified to the point of being wrong. It depends on many other factors, primarily the amount of RAM the card has on board and the current cards OpenGL performance (You do realise that nVidia has generally had better OpenGL support, right?
). That will have a larger influence on viewport/OpenGL speeds on larger scenes in most cases (I do assume you mean viewports and not rendering here
)