The ATI card is probably old enough to make it an upgrade, but all I've experienced and read about the FX series is that nothing nVidia produced out of that line was really a solid equivalent to ATI's counterpart (so a 9600 is better than a 5600). A great deal of the line failed to perform better than the 4xxx series' equivalents even. In the end, it's probably the increased feature set that would make it even worth bothering opening the case. Pixel Shader 2.0 is required by a number of games, and I'm fairly sure the 8xxx/early 9xxx cards don't support it, while all of the FX line does.