I agree, go with the quad, the cost up front is less than buying 2 CPU's and he will notice a difference with it.
Overall a nice build, it doesn't have a lot of options for upgrade, but as a stand alone build it will be fine.
Limitations:
Since the mobo only supports a single PCIex16 slot, the option of purchasing a 2nd video card at a lower rate in the future to extend video performance is not an option.
Also, PSU only includes a single PCIe connector.
Max output on the PSU is ~395w on the 12V rail, and and assuming you run it at a max of 90%, you have 355w avalible to work with.
With your current components you are sitting around ~270w
If you add two cooling fans to the tower, you will move that up to ~285w
If you where to add an additional hard drive and a blu-ray drive to the tower, it would go to ~330w(reasonable upgrades in the next 2-3 years)
It is likely that the PSU will be large enough for just about anything you could do with that motherboard, but note that should he want to overclock his CPU and/or Video card, it would limit the number of drives he could support.
Note:
-4 drives as a combination of optical and magnetic storage
-Less than 4 total drives if overclocking
-X2 video cards draw nearly as much as crossfire/SLI combos, would be questionable if there is enough power, likely not a future upgrade option
