If your motherboard supports newer AMD CPUs, it wouldn't be a bad idea to upgrade. The AMD's first generation FX series were/are junk. They didn't perform any better than Phenoms. The x3xx FX chips are quite a bit stronger than the x1xx FX chips. What motherboard and PSU do you have?
Also, forget about the 9590. There's no reason to buy it when it's an overclocked 8350.