[Stuart]

I would assume the quad core CPUs would be more of an advantage if you were to use the machine as a server on the network you submit jobs to. It would still need a fair amount of processing power to manage these jobs, and that wouldn't necessarily be something that would make efficient use of a massively parallel processing system (which is what GPUs tend to be).

Also, most versions of Windows and Linux are not optimised for massively parallel systems.

Also, you may need a fair amount of processing horsepower to send and recieve data to/from the tesla system. After all, if you need the kind of processing power these things offer, you will be dealing with terabytes (possibly many terabytes) of data.