This is for a Dell gaming PC (XPS 630) but it's primarily used for work stuff (software development, video editing) not so much for high end gaming (I'm still playing Star Craft )
My main criteria is NOISE and secondarily performance for the above types of applications.
-nVidia GeForcre GTS 240, 1024MB (concensus is this is just a supercharged GT 9800) and not as fast as the GTS 250. view Specs.
-ATI Radeon HD 4870 1024MB
I've read opinions that the Radeon is a bit loud (but they weren't comparing it to the GeForce).