For the graphics card, use MSI afterburner and up the clock speed to 998MHz and the memory to 1,996MHz, which will give you a 2-3fps boost in games. This can make or break games sometimes, depending on who much you value your FPS. Don't overclock it too much, because your system will overheat.
When windows 8 comes out, you can upgrade to it for only $15.00 because of a special offer microsoft is running.
For top of top of the line gaming (with that power supply) see if you can get a Nvidia GTX 680. They are the top of the line graphics card and are very power efficient (the GTX 590's have the same performance, but use almost twice the power.) However, GTX 680's are $500.