My sister was running out of disk space and some of her apps like Photoshop were running slowly and crashing. I decided to upgrade the RAM from 4gig to 8gig and put in the highest capacity HD I could find.
The repair went smoothly, except I didn't seat the bottom RAM chip correctly, so I had to disassemble the machine a second time to reseat it.
Be very careful with the bottom RAM chip, it is difficult to pull out and difficult to seat. Push it in all the way and make sure the grooves line up with the tabs.