I don't suggest the 7850 as it is of an older design. If you have the money, the AMD Phenom II X2 550 Black Edition Callisto 3.1GHz
will be a better chip as it has a newer design, is more efficient, and has greater cache. Sadly, that motherboard does not support it but it does support other Phenom II's. If you want the 550, the inexpensive GIGABYTE GA-MA770-UD3
will support it. AMD labels all of their highest performing CPU's as Black Edition. These processors have the highest CPU clock speeds for their class (dual, triple, or quad core) and an unlocked multiplier. The unlocked multiplier makes overclocking very easy, but even if you don't OC, the speed benefit from the stock settings still make the Black Editions very attractive. I suggest using the IDE drive as a slave due to its slower speed and put the OS on a SATA drive, if possible.