While your PSU might be able to spew out enough watts, it may be useless as it only spews them out along the wrong voltage rails.
Your computer needs power at a variety of different voltages. A PSU has several different rails, each supplying one of those voltages. Say your computer draws 15Amps along the 12V rail (~150W drain on the 12V rails), if your PSU supplys 470W, but the combined current rating on the 12V rails is 10A, your PSU will not be able to properly power the computer. Generally, the greatest wattage load on a computer is through the 12V rails, as they supply the graphics cards (which chug power like theres no tomorrow).
Any ideas what your PSU make and model is?
is an example of the data you need. If you click on the specifications tab, and scroll down, under 'output', you can see that this PSU has three 12V rails, each capable of 18A, which is very good for a 520w power supply.