Decent build, but I'd recommend a few changes.
Get a smaller PSU. 500W is plenty for a GTX560Ti. Get the Antec Earthwatts 650W from Amazon for just $60.
Go for the X4 955, and used the saved $$ to get a GTX570 or HD6970.
The Hyper 212 Evo is considered a better cooler than the N520.