Yeah you should be maxing it out at 60fps no problem. I do fine on maxed settings excluding aa/af and view distance @ somewhere hovering around 50fps.
With a that texturepack combiner mod (using the "lite" versions of the mods) I am around 30fps, I do need to turn down some settings like view distance, I think I have it set to 12. Been a while since I played so.
Heres my specs (your cpu is vastly superior)
Athlon 2 x3
6870 1gb
4gb ddr2
etc, etc, etc.