Windows Longhorn build 4000

6.0.4000
Build of Windows Longhorn
Screenshot
OS familyWindows NT
Version number6.0
Build number4000
Architecturex86
Compiled on2002

Windows Longhorn build 4000 is the first currently known Milestone 4 build of Windows Longhorn, which is mentioned in the setup of builds 4005 up until 4033, where it states that a user cannot perform an upgrade installation on a build lower than this build.