[2] Windows NT 4.0 is a preemptively multitasked,[8] 32-bit operating system that is designed to work with either uniprocessor or symmetric multi-processor computers.

It remained in use by businesses for a number of years, despite Microsoft's many efforts to get customers to upgrade to Windows 2000 and newer versions.

[16] Although the chief enhancement has been the addition of the Windows 95 shell, there are several major performance, scalability and feature improvements to the core architecture, kernel, USER32, COM and MSRPC.

There are new administrative wizards and a lite version of the Network Monitor utility shipped with System Management Server.

This eliminated a process-to-process context switch in calling GDI functions, resulting in a significant performance improvement over Windows NT 3.51, particularly in the graphical user interface.

This, however, also mandated that graphics and printer drivers had to run in kernel mode as well,[23] resulting in potential stability issues.

However advanced hardware accelerated Direct3D and DirectSound multimedia features were never available on Windows NT 4.0.

[25] In early releases of 4.0, numerous stability issues did occur as graphics and printer vendors had to change their drivers to be compatible with the kernel mode interfaces exported by GDI.

The change to move the GDI to run in the same process context as its caller was prompted by complaints from NT Workstation users about real-time graphics performance, but this change put a considerable onus on hardware manufacturers to update device drivers.

Previous versions of Windows NT included the Task List utility, but it only shows applications currently on the desktop.

The task manager offers a more convenient way of getting a snapshot of all the processes running on the system at any given time.

Direct hardware access was disallowed and "misbehaving" programs were terminated without needing the computer to be restarted.

Third-party device drivers were an alternative to access the hardware directly, but poorly written drivers became a frequent source of the infamous error known as the Blue Screen of Death (BSoD) that would require the system to be restarted.

[30] In spite of shipping a year later than Windows 95, by default there is no Legacy Plug and Play support and no Device Manager on Windows NT 4.0, which greatly simplifies installation of hardware devices (although limited support could be installed later).

[45] In addition to bug fixes, the service packs also added a multitude of new features such as Ultra DMA mode for disk drives along with bus mastering, newer versions of Internet Information Services, user accounts and user profile improvements, smart card support, improved symmetric multiprocessing (SMP) scalability, clustering capabilities, MMX / 3DNow!

[46] Microsoft released five revisions of the Windows NT 4.0 Workstation and Server Resource Kit (original release plus four supplements) which contained a large number of tools and utilities, such as desktops.exe which allowed the user to have multiple desktops, as well as third-party software.

Microsoft stopped providing security updates for Windows NT 4.0 Workstation on June 30, 2004, Windows NT 4.0 Server on December 31, 2004, and Windows NT 4.0 Embedded on July 11, 2006, due to major security flaws including Microsoft Security Bulletin MS03-010, which according to Microsoft could not be patched without significant changes to the core operating system.