Shouldn't skimp on the PS quality if you plan to have more than one videocard in a system. Pick any of PS from reputable brand like Corsair, Enermax, Antec, or Thermaltake.
Just make sure the 12+ line has enough Amp for the cards, usually stick with single rail of V12+ for best result. And take Crossfire/SLI certification as an indicator.
Thanks for the tip! I'll keep this in mind when I select another one. Hopefully the one I have will last.