how scalable is a mac pro? for instance, if i purchased an octa 2.26 ghz now, could i upgrade it when nehalem ex 8 core chips come out? if i purchase a quad, will it have 2 sockets to allow me to add a processor? what about graphics cards? i just found out a gtx 285 is available for mac (apple does NOT make this info easy to obtain, why?? something holding me back from even considering mac pro's was the awful graphics cards that came w/ the system) i understand the design lends itself to easy access, but is swapping processors as simple as it sounds or not something someone w/ absolutely NO experience altering a computers innards should attempt? im envisioning something like popping something out & popping something else back in, but i have a feeling its much more complex than that. im not looking to buy in the very near future, but perhaps next iteration, if its by early '10. i just worry about upgradability. im willing to pay a premium for OSX access & other plusses, but its for naught if in 2 years time the systems graphics rendering ability is completely dead in the water, or the CPU cannot be upgraded beyond average-high end.