350W should be sufficient, provided its a quality brand like Antec, Toptower or Enermax.
Though you may need more for really extreeme overclocking. (unlikely though)
<b><font color=purple>[Rik_]</font color=purple> I wonder how many people have made their own phasechange system?
<font color=blue>[LHGPooBaa]</font color=blue> I get phasechange whenever i eat a hot chillie