5200 is complete crap. ATI pretty much owned nvidia with the 9xxx series against the nvidia FX series. I know this first hand. I have an FX 5700, two friends of mine have the 9600XT and it destroys mine performance wise.
Out of those two definitely the ATI, but turtile makes a valid point, but seeing as how you said you already have them and not buying I guess it doesn't matter