Microsoft Corp.'s Longhorn Server builds 5381 and 5384 offer testers the first look at the server operating system. Longhorn Server expands the easy configuration features of Windows Server 2003. It also has a new TCP/IP stack and offers additional performance and functionality improvements in most of its core server roles. Longhorn Server is expected to be available at some time after the release of Windows Vista, the client portion of Microsoft's program. Many organizations are likely to upgrade to Longhorn Server before moving to Vista, however. The server upgrades will require handling fewer computers and will provide more value per upgrade than will upgrading the client portion. Sites that run Windows 2000 Server and 2003 Server should start to evaluate Longhorn Server as soon as they can. Longhorn Server is based on the same code as Vista. What it lacks, however, is the new Aero Glass, 3D-like interface and Aero options of the desktop-oriented product. Longhorn looks like Windows 2000, and in testing, it was much faster and more predictable than Vista to date. The major new feature of Longhorn is the Server Manager. It is built on the Microsoft Management Console (MMC) Version 3, and it represents an outgrowth of the 'configure my server' dialog that was launched by default in Windows Server 2003. Instead of acting as merely a starting point, however, Longhorn's version collects nearly all the operations that users would want to conduct on a server. Testers especially like the Task Manager-like views that provided a significant amount of information.