It depends what you will be running on it. What gfx card you be using? should be enough anyway but if you want to go for something that will definetly be ok then look here:
i dont like its +3.3V amp rating only 24A , also on the testing page the +12v dropped way too much , also topower isnt a well known psu company so i wouldnt get any of their psus , anyway that aint enough info, what processor/how many optical drives/hard drives/and do you plan to overclock the processor?