A few weeks ago, InsideMacGames posted an
He notes that (at that time) a Dual 500mhz/G4 with GeForce 2 MX runs Giants at approximately the same speed as a 1.3GHz Athlon, 266MHz frontside bus, PC2100 DDR Memory, GeForce 3.
More interesting to those of us waiting for our Dual 800's to arrive... Tim Wood comments regarding a 867mhz vs Dual 800mhz in non-multithreaded games:
For a game that's not multi-threaded, it will probably be similar in speed to the 867MHz. Even though your game is not specifically multi-threaded, the sound libraries on OS X take advantage of both processors. So the sound will be offloaded to a separate processor. So you'll make up some of the time. I don't know if it will be 67MHz worth of time, but it'll be close.
