S Vegeto said:
By updating my gfx card to Radeon latest/nVidia latest will that improve my speed or only graphic quality?
It may improve speed a tiny bit, but it's unlikely it'd be anything noticeable unless your current graphics card is uber old/feature lacking, same with graphics quality, you wont notice much difference unless your current card doesnt support PS 2.0.
Dolphin's speed is more dependant on the speed of your cpu.