There's not much point to using a quad-core processor at this time, as Dolphin's core is currently single-threaded. Processors have improved a lot, but don't overestimate the improvement. Even on decent machines (prior to Core 2) 10 fps was difficult to attain in-game. An overclocked Core 2 will be better, but six times better?
DirectX 10 may or may not improve things
if an emulator is optimized to take advantage of it. (Gamecube graphics are pretty simple compared to what modern cards can handle, but it's
possible other calculations
may be able to be off-loaded to the graphics card.)
Bare in mind that even if you had a processor fast enough, Dolphin is still very much a WIP and is very buggy (Wind Waker crashes when you get your first item). As a side note, we haven't broken the 5GHz mark - in fact Core 2's have slower clock frequencies than the NetBurst line (Pentium 4, Pentium D, current Celerons), but their more efficient architecture makes them much faster per clock cycle. Sorry to burst your bubble.
