I'm not up on all the latest CPU and mobo options, but I will say that you might benefit from holding off a little while if you don't absolutely need a new system right now. All of the current video cards are running on tech that has been out for a while and is due to be replaced sometime in the coming months. You can definitely get good performance with the current generation, but even the most high-end cards (like the GTX 580) have GPUs that were introduced a year ago. There hasn't been any word on exactly when nVidia or AMD might release their new tech, but it's expected to be early next year and could be a significant leap beyond the current options thanks to new 28nm construction...
Not to mention the 580s are really expensive. Considering that you can get a pair of 460s for less than the price of one 580, run them in SLi, and get better performance. Now running 2 580s in SLi, that would be bad ass but it would blow most of your budget.