Jesus these naming schemes are way to confusing. Engineers should not be given the task of coming up with this ****.
It Should be like this:
i9 High End Hex (6) Core
i7 High End Quad
i5 Average Quad
i3 Dual Core
Then the number indicates the series, so 5xx is 45nm, 6xx is 32nm, 7xx is 28nm.
Then the next numbers indicate speed/exact model:
Eg
i5 520 (2.1ghz)
i5 530 (2.4ghz)
i5 540 (2.6ghz)
i7 650 (2.6ghz)
i7 660 (2.9ghz)
If they did that it would be heaven.
PLUS: They have really messed things up by making the new 6 core cpu's in the i7 range. WTF?