Can anyone explain to me why the powermac dual 2.3GHz G5 was able to keep up with the Dual 2.5GHz model. Macworld explains it was because of the hard drive? I thought the 250GB found in the 2.3Ghz was the same speed as the 160GB in the 2.5Ghz model, 7200rpm. Why would one be faster than the other? Powermac G5 benchmarks - Macworld.com The reason I ask is I own a 2.5Ghz model and if I can speed it up by replacing the hard drive, it is something worth doing.