Nae bother any more hassle just come back, any of the ATX 2 PSUs are compatible its just the older ones have different number of pins for connecting to the mobo, new boards have a 20pin then a serperate 4 pin, old ones have a single 24 pin, but are easily modified to fit.
The one it comes with though is fine its compatible, should be a nice little system. The gfx card should be able to take a bit of an oveclock if you want extra speed and so can the CPU, for the gfx card i use ATI tool to overclock, gfx card overclocking is the simplest form of overclocking and it is the most common. You dont have to though i just thought you might want to i did and the card is supposed to be a good overclocker.