Personally, I'd do neither, as it stands the current system should be well balanced and powerful enough to play all games at high settings at such a low resolution.
Adding a GTX770 class card will be an upgrade, but it'll be wasted at that resolution, and severely held back by the current CPU.
Moving up to a i5 is the reverse, the CPU will be held back severely by the GTX560Ti, even at such a low res.
Only thing I'd change right now is that awful PSU.
Hold off until you can upgrade to a better balanced build: the i5 plus at least a GTX770 class card and a 1080 monitor-trust me on the monitor, a 22" 1080 display will be a revelation in clarity over the current display.
thx, ill probably upgrade both the pc and the graphics, just was wondering whom should I upgrade first and which one would give me a better improvement in the meantime,
and thx for the suggestion, ill probably consider upgrading my monitor before the others.