That cpu should have no problems pushing that video card to playable frames at typical resolutions. That cpu is actually good as far as dual core performance is concerned. If you have a proper mobo see if you can unlock the other 2 cores or at least a third core. That should definitely dispell whether its a gpu problem or not.
Maybe see if you can get your ram one speed grade higher. Example from 667 mhz to 800mhz. Then see what improvment, if any you can get then. Or even better see about doing some kind of small oc on that 460 card and see what the numbers look like.
Theres many ways to check for a bottleneck, like underclocking/overclocking different components to see how performance responds, ect.. So just pick one your willing to do and see what happens. I would say try doing a higher cpu oc but unless you have ACC you may be stuck in that 3ghz range.
Jason