MattyB13 :
You can run pretty much anything, but definitely not on ultra or high for some games such as Crysis 3 or BF4. 8gigs of ram and a better GPU would make you happy if you are willing to save a little more money.
Should mention a 64 bit OS. 8 GB of ram, (1333 is good but 1600 if you find a deal)
Sometimes there are shellshockers on newegg where you can get a 660+ for the price of the 650 ti boost. If in no rush wait for the holidays when prices go down, and more offers. If you want it now, then look wisely.
Don't cheap out on what will be powering your PC, thermaltake, corsair, seasonic, NZXT, evga, antec are some of the reliable PSU brands.
Case, do you want looks if you'll be focused on gaming- you can get a good mid tower for around 40 bucks with plenty of management and room. For a mid tower of course.