I was about to say the same thing... because I know so many people who make a living betting on benchmarks and whatnot. Real-world tests are nothing compared to benchmarks.
I think benchmarks are only useful as bragging rights for companies like IBM and Intel, so they can say, "My processor has higher integer performance than yours." "Oh yeah? Mine's got better floating point performance than yours!" *Nude mud wrestling by respective companies' female employees ensues*
There is much more to a system's performance than processor speed, as we all know. There is bus speed, disk speed, PCI speed, memory speed, graphics speed, and much more. The G5's have superior technology in almost all of these fields, and that is why they beat the PC's in real-world tests.