Best Wattage for PC Build?

[Demuny]

Hey there.
I'm new to PC building, and I have almost gathered up all of the parts. My specs are:
G-SKILL Ripjaws X 8 GB 1866 RAM
HIS IceQ HD 7870 Ghz Edition
AMD FX-6300 Vishera
NZXT Phantom 410 Red Mid-Tower
Seagate Barracuda 1 TB 7200RPM Internal Bare Drive
ASUS M5A97 LE R2.0
Windows 8.1

What is the best amount of wattage for this build? I don't want to go overboard, and I don't want too little. Thanks for the help.

 

[AtomicSheep]

I'd say 600watts is a good place to go for.