However if you were to spend a little bit more and go for the Phenom II X2 550 you would see a much larger improvement in gaming. The Phenom II series has their full 6mb of L3 cache which really helps with gaming and some other applications. Heres a comparison with the 550.
^That is true, AM3 processors have both memory controllers, (DDR2 and DDR3) they will work in most (most) any AM2+ motherboard, and they will work with either DD2 or DDR3 memory.
But you cannot use a AM2+ processor in an AM3 board. The AM2+ processors only have the DDR2 memory controller, and so they will not work on an AM3 board that requires DDR3 memory.
That is the difference between the 2,, the sockets are actually the same.
My MBO is Asus M2N-MX (it doesn't support AM3 cpu), and i am planning to upgrade to Asrock A770DE+ (AM2+/AM3 support, DDR2). This way i can keep my DDR2 ram and my Blacky CPU until i upgrade to an AM3 quad.
I'll probably get the board for Christmas and I'll get the quad when new games come, because i play just COD: MW2 now.