Anything Geforce 7xxx series or better should be sufficient, don't know about ATI cards. Just stay away from the LE (Low End) and Turbo Cache cards else it could bottleneck your performance.
I would suggest a better processor, I don't think the one you currently have would garner decent performance in Dolphin even with an overclock. The likelihood of you buying a new processor just for Dolphin is slim to none I guess, we might be able to offer advice so you can tweak your current setup to get better performance but you'll at least need a better graphics card.
I would suggest a better processor, I don't think the one you currently have would garner decent performance in Dolphin even with an overclock. The likelihood of you buying a new processor just for Dolphin is slim to none I guess, we might be able to offer advice so you can tweak your current setup to get better performance but you'll at least need a better graphics card.