"What is important when shopping for hard drives is the storage space, rotational speed, amount of cache, and of course the price. Currently, for desktop computers, 7,200 RPM SATA II hard drives are the most common type of storage. For enterprise and business, there is SAS, which stands for Serial Attached SCSI.

Although SAS HDD's are primarly aimed for the enterprise market whose main goal is to achieve the highest performance, the fact that you can find these drives in speeds of up to 15,000 RPM makes them a good candidate for enthusiasts as well. Current desktop SATA HDD's have rotational speed of either 5,400 rpm or 7,200 rpm. For the enthusiasts, SATA drives can be found in speeds up to 10,000 RPM. SAS, on the other hand, can be found commonly at rotational speed of 10,000 RPM and 15,000 RPM."