Memory

I have so many pictures & documents on my pc, that I am in need of some more computer memory. I try to keep things cleaned off, but it still gets so cluttered. I do try to save things to disks every 3 months & it helps alot. But to have more memory would help more, I think. It would keep my pc running faster & smoother. Our pc is 6 years old & there have been tons of upgrades since we bought it.