So my current fluently played game is Aion, I can play it somewhat decently on my struggling 9400 GT.
My question is, what would be the best upgrade within my price range of 80~160USD to play at least on high if not maxed settings (using the games BASIC engine, not the HD engine).

Note: I normally play with shadows off no matter the game, along with keeping anti-aliasing at a lowest setting or off all together.