On your power supply question
http://extreme.outervision.com/PSUEngine says 542W crossfire
http://images10.newegg.com/BizIntell/tool/psucalc/index.html?name=Power-Supply-Wattage-Calculator says 907W
A 650W psu might be able to do Crossfire. But if I was you and worried about having enough power for crossfire I'd just get a 1000W power supply from Seasonic (X series) or Corsair (HX or AX series) and stop worrying about it.
And unless you are attached to that Define R4, I would get something with more airflow to cool down a crossfire setup.
I would look at a NZXT Phantom 630, or something else from NZXT, or
http://www.newegg.com/Product/Product.aspx?Item=N82E16811146101
http://www.nzxt.com/
Cooler Master Storm Trooper
http://www.newegg.com/Product/Product.aspx?Item=N82E16811119245
or the white one
http://www.newegg.com/Product/Product.aspx?Item=N82E16811119260
Get low profile ram. Like this corsair stuff so you don't have problem with cpu cooler fitment.
http://www.newegg.com/Product/Product.aspx?Item=N82E16820233186&Tpk=corsair%20vengeance%20low%20profile&IsVirtualParent=1
For SSDs get a Samsung 840 pro or a Crucial M500. A Crucial M500 480GB SATA 2.5" is what i would choose if I was buying an SSD right now, it is $394.99.
On the graphics card. I would get a 7950 or a 7970. I like my Vapor-X 7950, it play all my games (Bioshock Infinite, Crysis 3, Far Cry 3 Blood Dragon, Team Fortress 2, Star Wars: The Old Republic) very well. The Sapphire 7970 you chose will serve you very well. Watch for sales and be ready to buy it, when on sale they go quickly. Other 7950 and 7970 brands I would consider would be Msi and Asus.
Lastly if you chose a case that has the option to mount more case fans, do it and fill up all slots. Doing so will make your components run cooler and last longer. Get your case fans from NCIX because they usually have them for cheaper than elsewhere. If you want quiet case fans that are reliable go with Noctua fans.
Where to buy fans
http://us.ncix.com/products/index.php?minorcatid=1164
To Ksham. The OP never picked the 7970 vapor x. He picked the dual x
SAPPHIRE 100351SR Radeon HD 7970 3GB 384-bit GDDR5 PCI Express 3.0 x16 HDCP Ready CrossFireX Support Video Card OC with Boost
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202008&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=