Well if you want insurance, spend the extra and get the new Antec 510 watt that should be out real soon. They have adjustable pots inside and usually better voltages than the Enermax. Combined 3.3v & 5v power will probably be higher to.
PC power & cooling do high spec 450 & 600 watt psu with 1% rated fluctuations but you will pay for it.
Have a look at
Antec's site