You don't need 12gbs of ram. Especially when a 4gb kit is like $40 and that was $180. There is also no reason to spend that much on a gtx 460. You could probably get a 570 or an HD 6970 which is much, much better.
You might also want to move up to a 700w power supply. That won't really add any cost because the 600w that you chose was actually quite exsnakeve.