No upgrades required,
Continue on and collect money !
You could probably get another 4890 cheap somewhere and double your gaming performance in most cases. Other than that, an SSD if you already don't have one.
I would say upgrade that 4890 to a DX11 card, but IMO at present there is no point. As others have said keep saving and just wait for a worth DX11 apart from BC2(which looks no different in DX11 mode over DX10).