JimFI

^^ this
 
Plus better memory. Any one of the following would be reasonable choices:
http://www.jimms.fi/tuote/HX318C10FWK2%2F8 http://www.jimms.fi/tuote/CMZ8GX3M2A1600C9 http://www.jimms.fi/tuote/KHX16C9T3K2%2F8X http://www.jimms.fi/tuote/F3-14900CL9D-8GBSR http://www.jimms.fi/tuote/BLT2CP4G3D1608DT1TX0CEU http://www.jimms.fi/tuote/KHX1600C9D3P1K2%2F8G

1. You don't NEED a better PSU, but you defenetly SHOULD get a better one. Just get a Corsair CX600, it's just a few bucks more and will do the trick.
2. For storage get rid of the unnecessary WD Black, get a WD Blue or a Seagate and grab a SSD.
3. For OS it's really a personal choice. Windows 8.1 is newer and gets you perfomance boosts over Win7 in some games (Battlefield 4 up to 50% depending on CPU & GPU). I'd go with Windows 8.1, you'll get used to it.
The rest seems good, altough I personally hate ASrock mainboards and would choose an ASUS or GIGABYTE mainboard.

What is your budget first?

You will need a better PSU, VS series are for entry-to-mid level components, your CPU and GPU are quite high-end, the VS is not enough, go for RM series
 
For OS, pick windows 8.1, it boots straight to desktop unlike windows 8 and more importantly it gives you better gaming performance

uhh dont start a flame war for 8 and 7 please choose yourself or look over some old topics. overall seems you're preparing for next gen game tide and i wouldnt change a thing but add a thing: Samsung 840 EVO 120gb SSD

Wasn't this posted like 5 minutes ago?