Getting a semi-gaming pc

Hi!
I want to get a new pc which I will use for gaming among other things.
I am not a real pc gamer, so I don't need need a real gaming pc, just one that is decent and can play games at decent settings.

I was thinking about a pc that comes with a AMD® A8-5600K (4x 3,6 GHz) CPU, is the ok (if I get a decent graphics card) or is that too weak?

I was planning on spending 150 euro € / 200$ or less on the graphics card and found these:

• Radeon Sapphire 7850 HD
• GeForce GTX 650 Ti Boost (1024MB or 2048MB version?)

Are these ok (also to compensate for the possibly weak cpu?) and which of these would you recommend?
If it depends on the games, for the moment I can only think of Starcraft 2 Heart of the Swarm (and Legacy of the Void once it comes out) and Phantasy Star Online 2 which I want to play.
Also, some GCN / PS2 emulation, I hear that requires a good gpu.

Also, is 8gb ram enough or should I rather get 16?

Thanks.