Do you recon it would be possible to emulate the GameCube with curent chip sets (Anthlon 64 and Core2 Duo)???
If we're having trouble with N64, what makes you think the GC is viable? You're talking about significantly increased complexity, by leaps and bounds.
Interesting thing about the GameCube is that it uses a PowerPC processor and an ATI video card.
On a multicore PPC and on a machine with an ATI video card, it may just be possible to actually run the two main processing units directly, and use the other cores for working out the extra sync math and quirks.
Hence why I think emulating the XBox shouldn't require as much horsepower as say the PS2. Since when parts aren't actually emulated, but are able to be ran just like the original (if possible), extra overhead for that component isn't needed.
The "ATi" chip is actually a design by a completely different company that ATi bought not long before the GC came out. It's a very unusual design(Search through the forums at www.beyond3d.com), and wouldn't be able to be emulated quite like that.
It does have some rather standard graphics features, mind you. It's the TEV that's the bitch.
One thing about GC emulation that I like: you should be able to reuse at least some of that code to do Wii emulation.