Building a gaming computer. Do these components work together?

Joshua Asked: Building a gaming computer. Do these components work together?

What I am looking at:

Motherboard: http://www.verkkokauppa.com/fi/product/14945/dcfvm/Asus-M5A78L-LE-760G-AM3-ATX-emolevy

CPU: http://www.verkkokauppa.com/fi/product/13272/ddtbb/AMD-FX-4100-3-6-Ghz-4-core-Black-Editon-AM3-suoritin

Graphics card: http://www.verkkokauppa.com/fi/product/11933/ddjvf/MSI-N550GTX-Ti-Cyclone-II-1GD5-OC-NVIDIA-GeForce-GTX550-Ti

RAM: http://www.verkkokauppa.com/fi/product/54894/dfjdx/Kingston-HyperX-4-GB-DDR3-1600-MHz-CL9-Red-Limited-Edition

PSU: http://www.verkkokauppa.com/fi/product/7353/xtqn/Codegen-Dual-Switching-550W-ATX-2-0-P4-ATX-virtalahde

I have the rest of the components.

Is this a good enough gaming computer for a cheapish price and do these components work together? Games I am looking to play are games like WoW, Rift, Tera maybe Battlefield 3, that kind of stuff.

I am not sure about the PSU (Power supply unit) I have a 450watt one already, but maybe it isn't powerful enough to run these components? What do you think? Should I buy the 550watt one as listed above or a better one?

Any feedback would be very helpful.

THANKS! Josh and Janina.