The original hard drive was too small making the computer very slow.
Followed the directions without any problems. However, I once worked as an electronic technician repairing two-way radios, so I am familiar and comfortable changing out the hard drive. I thought that others without my experience would have a few problems. For example, discharging your body's static electricity; having separate places to put the different screws; working slowly; do not force anything; ribbon connectors would not be understood; looking over everything as you go along - including other areas. Most important is how to get your computer back to the same state as before. I spent some time researching this; I fear others may end up with a computer with an empty hard drive.
Have two sets of instructions. One for computer savvy (hardware and software) technicians, and another very step-by-step for those brave souls who really do not know as much as they think. Include in the instructions little lessons on hardware and software.