What you have looks perfectly OK, with power for the Arduino coming via the USB. However, why not also connect your +12 volt supply into the Arduino power system and let the Arduino self-select between USB or main power.
That's not a great idea - the 12V supply to the servos will be very noisy. If you do this you want another level of voltage regulation (such as a 10V regulator and decoupling) between the "raw" power and Arduino's Vin.
Also the 12V supply may be crowbarred on overload and reset the Arduino... In general separate supplies for logic and big motors is a good idea. If the maximum stall current for all the servos exceeds the power supply's rating, I would strongly suggest keeping supplies separate.
Actually looking at the PSU you select it seems to be a computer supply, not one designed for inductive loads... I would add generous decoupling.