if you look at the vue mark numbers over at cornucopia forums the best cpu (in terms of render speed) is the new core i7 although it might still be a bit overpriced as it only was introduced late last year and requires its own motherboard and memory. the next best and cheaper thing would be the above mentioned core 2 quad core.

vista 64bit with lots of ram will make sure you dont run into low memory problems with vue.

i dont know about graphics cards but i guess all the modern ones are ok.

if you really want to go crazy have a look at this link helmer.sfe.se/

hope this helps