Core Duo, Dual Core and me.

[MuMu]

I've recently acquired a mediocre computer with an E5400 Intel Dual Core CPU(2.70GHz) and decided to test it a bit on the SystemRequirementsLab. The problem is, many of the requirements are displayed in Core Duo settings, and while I do think that there's something that makes them superior to the DC(I'm very hardware illiterate, excuse me), I don't know what it is.

The one that confuses me the most is the minimum speed for the War for Cybertron game, a Intel(R) Core(TM) 2 Duo E4300 1.80 GHz. Even if the Duo is indeed more efficient than the Dual, is it that much that almost a 1GHz of difference still isn't enough?

Of course, the site could always be full of shit...