|Version of Microsoft Windows|
|Replaced by||Windows XP
Neptune (internally at Microsoft also known as NepTune) was planned to become the successor of the Windows 2000 family as well as the first consumer version of Windows under the NT kernel. It was under development in 1999, until it was canceled, along with Odyssey to give way for Whistler, which would be released as Windows XP in 2001. XP included a new login screen, help center and user accounts panel originally envisioned for Neptune. However, Activity Centers were eventually dropped. As stated in confidential Microsoft documents, Neptune was to be released in Q1 2000, planned to have 64-bit edition (referred to as "NT64") for the upcoming Intel Itanium processor, "Solar Coaster" (Unix Services for NT), Internet Explorer 6 (which was also in development at the time) and some Anti-Piracy features. There is evidence that five service packs were planned for Neptune.
A successor called Windows Triton was mistaken as a service pack, but as shown in Antitrust documents, it was actually a successor to Neptune which would bring minor updates and enhancements.
The following planned release dates come from PX07297.
- RTM: March 2000
- SP1: May 2000
- SP2: September 2000
- SP3: January 2001
- SP4: July 2001
- SP5: March 2002
Other Neptune SKUs
Microsoft Anti-trust documents from Neptune era indicate that Neptune was to have not only one, but several editions, namely "Entry-Level", "Standard" and "High-End", which could translate into these modern SKUs: "Starter", "Home" and "Professional / Server". It is unknown what these editions would actually become, if Neptune was ever released.
There are also several strings in file USETUP.EXE from Neptune build 5111.1 that clearly mention "Neptune Server". These references could be leftovers from Windows 2000, if all "2000" strings were simply replaced with "Neptune" during the rebranding process.
NOTE: some of the information provided in this timeline is based only on rumours or unconfirmed build numbers. Therefore, this timeline can not be taken as a reliable source of information.
- Early July 1999: Neptune build 5.50.5022.1 is compiled
- Around September 20, 1999: Neptune build 5.50.5067.1 is compiled
- Around October 26, 1999: Neptune build 5.50.5086.1 is compiled
- Around November 8, 1999: Neptune build 5.50.5095.1 is compiled
- Around November 17, 1999: Neptune build 5.50.5099.1 is compiled
- Early December 1999: Microsoft announced the details of Windows Neptune to a few testers
- December 10, 1999: Neptune build 5.50.5111.1 is compiled
- Mid-December 1999: Neptune builds 5.50.5116.1 and 5.50.5117.1 are compiled
- December 27, 1999: Neptune build 5.50.5111.1 is sent to selected testers
- January 21, 2000: Paul Thurrott reveals that both Neptune and Odyssey are cancelled and will be replaced by Whistler.
- March 20, 2000: Windows Whistler build 2211.main.000309-1512 leaks, though it looks a lot like Neptune it's an entirely new project