It is indeed the one that came boxed with the chassi, it's rated at 450W seem to be of part of the product line Smartpower. I feel 450W should be more than enough for my system as most of the components were driven by a 300W PSU before I upgraded.
As a sidenote, the Sonata II isn't as good at reducing noice as I had hoped, but the biggest disappointment was the Zalman CNPS9500 cooler which is quite noisy and a lower setting for the fan control would be desirable as my box is now cooler than it need be when running low-demand applications.