Are these computer parts compatible?

So I'm building my first pc and I'm scared because I don't really know if the parts are compatible...and if you guys have some first build tips for me that would be greatly appreciated. This PC is meant to be for casual use and light gaming (MineCraft, Sims 3, etc...) and I really need some input on my... show more So I'm building my first pc and I'm scared because I don't really know if the parts are compatible...and if you guys have some first build tips for me that would be greatly appreciated. This PC is meant to be for casual use and light gaming (MineCraft, Sims 3, etc...) and I really need some input on my part selection and if you guys suggest some better parts for the price that would be greatly appreciated! My price range is 600-620 roughly.

Specs:LG DVD Burner Black SATA Model GH24NS90 - OEM

Antec Nine Hundred Black Steel ATX Mid Tower Computer Case with Upgraded USB 3.0

Seagate Barracuda Green ST1000DL002 1TB 5900 RPM SATA 3.0Gb/s 3.5" Internal Bare Drive -Bare Drive

EVGA 01G-P3-1556-KR GeForce GTX 550 Ti (Fermi) FPB 1GB 192-bit GDDR5 PCI Express 2.0 x16 HDCP Ready SLI

PC Power and Cooling Silencer MK III 400W Modular 80PLUS Bronze Power Supply compatible with Intel Sandy Bridge Core i3 i5 ...

Kingston 4GB 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10600) Desktop Memory Model KVR1333D3N9/4G

ASRock 970 EXTREME3 AM3+ AMD 970 SATA 6Gb/s USB 3.0 ATX AMD Motherboard

AMD Phenom II X4 965 Black Edition Deneb 3.4GHz Socket AM3 125W Quad-Core Processor HDZ965FBGMBOX

Also, do you guys suggest buying extra cooling? If so, what extra should I get?
and how do I know what operating system to get? 32 bit or 64?
All help would be greatly appreciated...thanks!
3 answers 3