What size power supply would fit an e-Machines EL 1333G-03-W Desktop. How high of wattage can the board take?

Your computer came from the factory with a very tiny 220 watt power supply that is about as small as it gets. This is what you get with inexpensive computers and the failure rate is always high as the power supply is usually over worked trying to keep up with the power needs of the pc. The board will use no more power than it needs so you can install a high quality power supply. So I would recommend you install at least a 400 watt power supply and a 500 watt would be even better. Just buy a power supply compatible with your PC. Here is one good source for power supplies. http://www.tigerdirect.com/applications/Category/guidedSearch.asp?CatId=106&name=Power-Supplies