Welcome to Tom's Hardware Forums,
I will suggest 4GB of 1600MHz ram or 1333MHz with CL7 timings
Your APU choice seems okay but I am really not caring for the HD5450 as a complimentary GPU - I'd be looking at a HD6570 for about $60
I think that would give you the ability to play most games smoothly (if not at the highest resolution levels).
Hope it helps some