Just because a cpu has a higher clock speed doesn't necessarily mean its better. Its all about architecture my friend. The Nahalem architecture (i5-i7) is much more efficient than, say, the Phenom II or even the Core 2 architecture. Therefore, a 2.66ghz core i7 can easily best a 3.4ghz Phenom II, or a 3ghz core 2 quad. Hope that helped clear things up a bit.