Chaos is right about the PSU, the one that this prebuilt comes with is thinner and longer than a normal PSU, ignoring the dimensions of the case any regular PSU wouldn't even match up with the screw holes on the case so you wouldn't be able to secure it, the power input would be covered by the case and, above all else, the motherboard would be in the way of any other PSU no matter whether it was vertical or horizontal.
He's wrong about everything else, though, from what I saw in the images I looked at everything else is a standard component