Go with a 7870XT instead of the 660 Ti, it's cheaper and more powerful there is no reason NOT to get it.
You do not need that many watts on your PSU to run that GPU unless you plan on CrossfireX and even then it may not use that much, it will save you a few dollars. Stick to that brand though.
The samsung 840 series has a low lifespan look into the 840 pro series it's going to be a lot better than the one you have.
Other than those changes you are set for a LONG time.