Windows 2000 was a long time in the making. Windows 2000 Professional (instead of Workstation) replaced all previous versions of Windows in a business environment, desktop or laptop.

Windows 2000 Professional had plug-and-play support, an improved network for both wired and wireless networks, and full USB and infrared support, which was important for laptop users. Windows 2000 also included Internet Explorer 5.01.

The server versions introduced Active Directory, which was Microsoft’s first true directory service offering. Until Windows 2000, centralized accounts and management were based around the domain concept, using the Security Accounts Manager (SAM), which was a flat structure consisting of users, computers, and groups, with relationships to other domains via manually maintained, nontransitive trusts.

Active Directory was a true directory service that enabled Microsoft-centric networks to offer far more sophisticated solutions with a more granular management structure.

Windows 2000 also included a replacement for NT LAN Manager (NTLM) authentication: Kerberos, which provided a far more scalable authentication.

Windows 2000 provided a new administrative environment: the Microsoft Management Console (MMC). The MMC was a GUI shell that could load one or more snap-ins that provided administrative tool–type functionality (such as a Computer Management snap-in that allowed management of computer functions, such as services, disks, and so on).

Windows 2000 also introduced NTFS5, which had quotas and encryption. A recovery console came as a separate environment that the operator could boot to when a problem could not be resolved inside the OS.

Each version of the now familiar Windows 2000 Server line contained the same core OS but had different features and supported different amounts of processor and memory.

As of Windows 2000, support for MIPS, Alpha, and PowerPC dropped from the retail channel but could be obtained from embedded system vendors.

The three versions were Windows 2000 Server (the base version), Windows 2000 Advanced Server (support for addition processors and memory and supported clusters), and Windows 2000 Datacenter Server (support for large amounts of memory and CPUs).

Because of Active Directory and its different management structure, adoption of Windows 2000 was slow. It took time for people to understand Active Directory and its huge advantages over its predecessor.

Coupled with changes made to Exchange 2000, which had to run on Windows 2000 and Active Directory, migration was mainly a case of “when” and not “if.”