I just recently bought a MSI 760 OC, runs everything on ultra at around 60 FPS. The biggest thing to make sure of in a gaming PC is to make sure your CPU or GPU are not bottle necking themselfs anywhere. The CPU which you have stated seems to be average, a 4.3 boost couldn't hurt it, but that GPU is complete trash.
I would be surprised if you could run Runescape on 20 FPS