I would start by saying hello, secondly I would ask what is the make mode of cpu/ and motherboard not that I think either the GTX 560 or 650 will not work (and obviously the 650 performs better than 560) I am curious if a bottle neck can occur on your system.
also what games are you expecting to play (if any) with this system ?
lastly I would suggest an upgrade of memory yes, but I need to have motherboard make and model to suggest accordingly.