Most people think of 'NT' as 'WinNT 4', while in reality the term NT is equal to the NT series, which ranges from version 3 over NT5 (2000, XP, 2003) to NT6 (Vista).
The NT architecture was designed by a team lead by David Cutler, a former lead developer of VMS. It took them more than 4 years to combine the best of UNIX, VMS and OS/2 and create the NT architecture.
Summing up the changes in the new release ReactOS 0.3.7
* Improved x64 architecture support
* The start of a real MSVC compiler support project
* Kernel improvements and bugfixes in quite a few parts:
ConfigurationManager, IO Manager, KE, Memory Manager, Object Manager, Process Manager
* Network stack improvements: leakage fixes, increased functionality
* Filesystem driver fixes, making them more compatible with the Microsoft NT cache manager
* Win32 subsystem improvements and synching of most of the Wine usermode DLLs