Here is one discussion from C3D. There was a longer one, but i don't see it now. A search here would prolly turn up a bunch also.

My understanding is that some 3D programs use the 3D GPU(s)/Pipelines of your display card and some don't. Vue does not. So i would look at how your individual 3D programs use your display card to find out if it's worth spending a lot of money (and dealing with all the hot air high- end cards put out) required for a high-end card.

I'd say the main advice is to get a card that is very popular, so that your 3D programs are likely to support it - for example a mainstream ATI or nVidia.

In Vue 5 or 6, all you'll get from an ultra-fast display card is faster viewport preview refreshes - not faster renders.