as for getting a new one. It won't hurt to do so, but for a basic system your current model will be fine. don't overclock with the earlu EGVA PSUs though. only the gold, 2nd Generation models are really top-tier.
I like to keep it simple and use the Newegg power supply calculator. Its not as in depth as some other tools out there but it gives you a good idea of what will work. http://images10.newegg.com/BizIntell/tool/psucalc/index.html?name=Power-Supply-Wattage-Calculator
i put in my current specs and it said i was using more wattage than i actually had available, since i only have a 500 watt psu, it said my system would take 550... which just isnt true lol
as for getting a new one. It won't hurt to do so, but for a basic system your current model will be fine. don't overclock with the earlu EGVA PSUs though. only the gold, 2nd Generation models are really top-tier.