The only difference between those machines is the CPU. While the clock speed is lower, I wouldn't be surprised if the current quad i7 is much faster than the 4

The only difference between those machines is the CPU. While the clock speed is lower, I wouldn't be surprised if the current quad i7 is much faster than the 4 year old quad. Which really only adds to the confusion - its really not easy to tell how much faster this years i7 is against last year's i7, since clock speed doesn't really matter anymore when comparing across architectures.