For most computers that are over 2 years old, a new hard drive can breath in new life. Hard drives come in a variety of capacities as well as speeds. Most of the time, the average computer comes with a hard drive that is less than optimal or has very little space.
The upgrade to a larger drive, whether is a faster mechanical drive or an SSD (solid state drive) can reduce boot up times, make applications launch faster, and make the general use of the computer a more enjoyable experience.