Im upgrading my system in a week or so, decided to go with amd scince im on a pretty tight budget, but I just cant decide which cpu to get. Im going to be useing the machine primarly to do a bit of vm work etc, with light gaming on the side(wow, eve online, mass effect). I know that some x3's have an unlockable 4th core, but im not counting on it anyway. Just wondering on which is the better cpu on paper at stock etc, though I probably will try a little overclocking, but only on the heat sink that comes with. Theres a $4nz differnce between them both( http://www.pp.co.nz/ is the place im shoping with).
At stock, the PhenomII will have an advantage in single and dual threaded applications and programs that don't use 4 cores. For the few programs that actually do use 4 cores, I'd say the AthlonIIx4 has a slight advantage.
If there is only a $4 difference, I'd probably get the PII x3 and try to unlock the 4th core. If not, the PIIs are good overclockers. (same with AthlonIIs)