Is this gaming rig good?? What can I do to make it cheaper?

So PLEASE read everything before answering, my questions wont be long anyway.
Is the rig iam going to build good? What can i do to make it cheaper? And should i buy an hd monitor or a 1600x1200? My video card is very good and i think that playing at a lower resolution will improve fps....is the visual quality that much better at 1900x1080 and is the fps increase worth the lower resolution??

THIS IS THE RIG

MOBO GIGABYTE GA-Z68X-UD3H-B3

CPU INTEL CORE I5 2500K 3.3 GHZ (NOT PLANNING TO OVERCLOCK FOR SOME TIME, IT WILL BE DONE LATER)

GPU GTX 580 1.5 GB

RAM 8GB (2X 4GB) 1600MHZ

PSU CORSAIR TX750W (IS THIS WATTAGE ENOUGH, IS IT TOO MUCH?? WILL IT BE ENOUGH FOR A GTX 680)

What do you guys think??

By no means am i going to get another gpu or cpu, so please dont sugest me to buy cheaper ones to decrease the price