Microsoft Windows NT
Windows NT 3.1 was the first version of Windows released by Microsoft that was not based on a DOS kernel. NT 3.1 used a clone of the Windows 3.1 UI, but, unlike Windows 3.1, NT 3.1 was a 32-bit operating system written from the ground up.
The Windows NT kernel was originally written to replace the kernel in OS/2 version 2, but Microsoft and IBM ended up splitting, and IBM did their own rewrite of OS/2 without Microsoft. Microsoft then took what they had written and turned it into a more stable version of their existing Windows OS.
NT 3.1 used the Program Manager, only slightly modified from the Windows 3.1 Program Manager. For starters, the NT Program Manager was user-aware, meaning, each user could have his/her own program groups. Most utilites and apps shipped with NT 3.1 were simply ports of their 16 bit counterparts, however, some stayed 16 bit and ran under the Windows 3.1 emulation subsystem.
NT 3.1 introduced services, the NT kernel's alternative to TSR's. Also, NT 3.1 introduced a new architechure for device drivers.
Again, File Manager highly resembled its 16-bit Windows 3.1 counterpart, except it included a few key NT features, such as the ability to set permissions.
NT 3.1 also included 32-bit versions of the multimedia apps shipped with Windows 3.1. NT 3.1 came in three versions, NT 3.1 Server, NT 3.1 Advanced Server, and NT 3.1 Workstation.
NT 3.1 is a good OS for an older computer that doesn't have much strange hardware. The main drawbacks to using NT 3.1 is lack of software and lack of drivers. I recommend that anyone thinking of running NT 3.1 as an OS look into NT 3.51 or OS/2 3.1.