I would suggest a 750w or better branded quality PSU. Your graphics card alone requires a 500w minimum add to that all your hard drives. Cpu and opticale drives, not to mention your heatsink fan and additional fans.
Here's a link to a program that will help you get a general idea of what power supply you'll need, This is by no means definitive but you should always get more than required.
Personally I consider the power supply as a very important core piece of hardware not to be skimped on. Hope this will help. Fabe
http://extreme.outervision.com/psucalculatorlite.jsp