TODAY, THERE ARE ESSENTIALLY two classes of 3.5" Serial ATA hard drives available to consumers: drives designed for desktops, and those targeted at the enterprise. Desktop drives make up the bulk of the market and tend to favor lower noise levels and faster performance with sequential transfers, while enterprise drives generally have quicker access times, longer warranties, and better performance with multi-user and multitasking loads.

For most folks, picking a desktop drive is the most logical choice. However, PC enthusiasts have long tapped enterprise-class hardware in search of a better performance. In fact, last year we named Western Digital's enterprise-oriented Caviar RE2 the best hard drive of 2005.

Nearly a year after the original's release, Western Digital is back with a 500GB flavor of the RE2 that promises faster performance and lower noise levels than its predecessor. Western Digital has also rolled out a 500GB version of its Caviar SE16 desktop drive that bears a striking resemblance to the RE2, setting the stage for an inevitable and epic comparison. Read on to see whether you're better off with an enterprise RE2 or a desktop SE16 as we test the drives against each other and a dozen of their competitors.