That's unfortunate, that board doesn't support the fx 8320. The 4460 is an improvement over what you have, but it's not leaps and bounds better. To save yourself some money, or present another option, the fx 6300 performs roughly the same as the 4460 and it's only $99. Either way you'll be getting what you want.
However, you'll want to verify which revision of the board you have, the earliest model doesn't support the fx 6300.