I went with the cases internal 420w PS, if something bad happens I'll upgrade to the Enermax 450 one.
As far as the power supply is concerned,, you've got 3 different types of DC output, 3.3V, 5V, and 12V. I couldn't find the information for the power supply in that case, but there other supplies show 15-18A on the 12V line. If yours is the "15A" version it probably is not enough power. Most people just look at the volt rating and assume that is the important number, but it isn't; the number of amps carried on the 12V line is more important, you powering an energy hungry processor and video card. And when your case heats up which includes your power supply the Amps will drop and the quality of the power produced by that supply will also deteriorate. Then stability of the machine will suffer.
If you wait till something "bad" happens it could be too late. Ever have a power supply pop and spew smoke? When it pops what will it take with it, the motherboard, the processor, the memory? It is not worth the hassles of using a marginal power supply.
Look at the 12V line of the Enermaxs and Antecs, there is quite a difference. Also you'll be sure that power is clean and stable-which makes for a happy machine.
With that being said, you may never have a problem with your current power supply.