$600 might allow you to squeeze an i5 in, but to better balance your rig, I've dropped it down to an i3 to allow for more graphics power. It is still an awesome CPU, and the budget with an i5 would have given us less to work with in the graphics department, which would have limited your machine.
The PSU might be a little too much power for what you'd need, but thanks to the code, the next step down would be more expensive anyway, plus the one given has the required power supplies for the recommended graphic cards. I'm sure people might have other opinions on the mobo, I don't usually overclock, so I just look for a reliable brand that has had many reviews for that particular board that has all the features I'm looking for. If you actually do the rebates, you'll save another $40 or so with the original set-up, so the graphics card would actually be a push compared to the cheaper 6850.