I have a few suggestions but the question I have is when do you plan on getting this?? You're 13 and you're looking at a build close to $2k. I understand you are going to be building/buying as you go those 580s are $499.99 each plus $100 for each block. Also I'm assuming you would have to buy the CPU, RAM, and motherboard all at once. You could use your 9600GT until you get the money for the 580s but I feel by then this build will be VERY different with Bulldozer and Ivy Bridge coming out.
Back to the main topic, here are a few suggestions:
Sparkle Gold Class 1250
You don't want to cheap out on a power supply.
What are you going to be doing that is going to need that much memory?? You don't need more then 4gb but the way RAM is dropping in price so much you can get a 2x4gb set for very cheap.
My recomendation is to get a pair of Samsung F3 1tb
and do RAID 0 with them. They are faster and much cheaper then the Western Digital Caviar Blacks. They are actually the same price as the Caviar Greens but perform so much better.
You are going to need more radiator to water cool all of that. The fans that come with the XSPC kit are pretty low speed too so you're definitely going to need higher static pressure fans and find a place to fit more radiators in that case.