also. in regards to your power usage. even with the gpu. im pretty sure you would only need the 500W to power this build, unless you have any radical additions to your build. Even then, the 600W would do it for you. to double check: use this webapp: eXtreme Power Supply Calculator
to put it into perspective. I have a sandy-bridge extreme setup for the cpu with the gtx 680. and i still would not use all of the 750W psu which im using unless I overclock. also. when looking for a psu there are a few things to consider.
1. brand name psu - no-names are unstable generally.
2. 80% efficiency at least
3. the form factor - the atx12v is the most common atm.
4. the types of cables.
if you want to read more into it and learn a little. newegg provides a neat little guide: Newegg.com - Learning Center,Power Supplies
also. if you have more specific questions, again. hopefully another member can help us out. or i will try and answer your questions. best of luck,