One big problem. It appears that you're planning on getting an intel X58 motherboard to go with your i5 build - this won't work. Intel X58 motherboards are designed for i7 9xx processors due to their socket 1366 - the i5 is on a separate platform, intel P55 for socket 1156.
Here's a good motherboard for your i5 - http://www.newegg.com/Product/Product.aspx?Item=N82E16813128412
Other than that, it is a decent build - i5 based rigs are great in terms of performance and value.