Modern hard drives are much more reliable than the disks of yesterday. However, they still are extremely complex electronic devices with moving parts that are subject to amortization. The high density of data storage provided by the modern disks allows for greater storage capacities and higher access speeds. However, with densities and capacities pushed to the extreme you have much more to lose should the drive fail. The hard drive is the most important component in your entire PC because it holds all that is of real value: your documents, digital pictures, email messages, your work and private data.