I would go for an i5/i3 and 7850 setup. You also don't need 630 watts. A good quality 500w PSU will run this system without trouble. Use brands like Antec, XFX, Corsair, Seasonic.
What i3/i5 do you suggest? the i5-2500 is 50 euros more expensive and looking at this chart (not sure if reliable) the fx-8120 is better.
Also the 7850 is a good 90 euros more expensive then the 7770. Is it really worth it if my most intensive game is witcher 2 (And id be satisfied if I can run it smoothly on medium settings)
The PSU is just as expensive as most 500w PSU's (52 euros) and a friend said this one is extremely quiet.