In that case i use a Nvidia FX5700 256mb Graphics card. it works great with both pc games and emulators. And its only about 100Euro so its fairly cheap as well.
I have to disagree, eventhough they arent as fast, they are inexpensive, decent GPU. If your a hardcore gamer, than you might want to go with something better, But they are a lot more expensive (like 100 USD more)