Replace the very expensive old graphics card with a Radeon 7850 for about $5 less
and increase the game performance about 30%
Then drop the psu to a 520 watt model which should easily have enough grunt
Antec NEO ECO 520C $40
http://www.newegg.com/Product/Product.aspx?Item=N82E16817371030
The 1866 MHz RAM voids the warranty on your processor . Use 1600 MHz . You wont see any performance decrease
That saves you so much you can afford a case that isnt totally hopeless . The gamma really is a a very poor case
At that price you can get a Corsair 200R
Or spend as much as $50 on something like the HAF 912
And if you are really desperate for an nVidia card [ why?]
then make all those savings , buy the 200R case , and drop the cpu cooler
and get one of these for $209
GIGABYTE GV-N660OC-2GD GeForce GTX 660 2GB
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125443