I think there really is no substitute for cores when it comes to compiling, which is why I went for the 6 core processor; I know that the Intel chips were faster per core but the only 6 core Intel chip at the time was just ridiculously expensive. That is probably still true.
Also I am not overclocking the Phenom II in any way; it's just a stock 1075T at 3.0 Ghz, for what it's worth.