The name Dell Optiplex does not just refer to a single computer, but to a whole line. The first Optiplex models were released in 1995 with the original Pentium processor. Optiplex computers are designed to meet the needs of Dell's corporate and business users more than consumers. This means that many Dell Optiplex computers come in small form factor cases for better portability, and include high performance networking features such as gigabit ethernet for use in a business environment.
Most include a dual core processor such as the Core 2 Duo E6600 and many fo the later Optiplex models even have SATA hard drives. These computers support both Windows and Linux operating systems, depending on user budget and requirements.