you have to get the Quadtro 4000 from the Applestore as an accessory - not part of a CTO build. See http://store.apple.com/uk/product/H3...co=MTY3ODQ5OTY for example in the UK store.

GTX285's are very hard to come by - some people in the US are 'chipping' the PC version to work on a mac. They seem to work ok - but its a risk you take using them.

Nev.