Memory is the cheapest hardware upgrade you can make these days. You can literally find quality memory for under $50. I did better and found a pair of quality name brand RAM sticks that you can get for under $100, the Corsair Vengeance 16GB (Two 8GB memory modules ) DDR3-1600 memory which you can purchase right at Micro Center for a mere price of $89.99. This 240 pin DIMM unbuffered RAM has pretty decent memory speed at 1600GHz. Probably the main attraction here is its nice size heat spreader which should keep your memory nice and cool.
Go to Micro Center now its sitting there waiting for you to buy it.