I have an old computer (Athlon II X3) that I use daily for school, work, streaming HD videos, and internet surfing. I currently have 4 GB of 1333 MHz RAM. What will improve if I upgrade to 8 GB of the same speed? I'm not ready to buy a new computer yet, I would like to upgrade a little and use it for another 3 years. I already installed a Samsung SSD and Gold rated PSU.