Windows 2003

Windows 2003 is an operating system coded and released by Microsoft Corporation.

Pre-Alpha
The first-ever build of Windows 2003 was released on May 1st 2001. The only change is the boot screen and theme.

This build has been leaked on 1st August 2001(Pretty fast).

Alpha
The second build of Windows 2003 was released on 1st September 2001 as Windows XP Home Edition 2.0 (joke made by MS coders)

This build has many, many changes:
 * Changed Kernel from 5.1 to 5.2
 * A small change on the theme
 * Changed color name od build from dark blue to green
 * Internet Explorer 6.1
 * Windows Media Player 9.0.01
 * First Attempt to add and finish Longhorn features (Fail)

This build has been leaked on 24 September 2001 (very fast)
 * And many, many more!

Beta 2
The third Build of Windows 2003.

Changes: This Build has been leaked on 30 August 2006
 * Improved security on Internet Explorer
 * A custom version of IE (6.3 with Security fixes and support for newer sites)
 * Added (On private build) Millenium Virus Scanner (By WinSec)
 * Removed completely com files (It caused problems, fixed right after release)
 * Second and successful attempt to add and finish Longhorn features

Pre-RTM/RC1
Fourth(Public) and thirteen(Private) Build, and final from building operating system has small changes: This Build has been leaked on 6 November 2007.
 * Changed Versions of programs (IE 6.3-IE 6.8 SuperSecure Edition)
 * Removed AntiVirus and replaced by Security Fixes
 * Added Firewall Support, CBE (Check-Before-Enter) Function added to IE

Final Build
Final Release of Windows 2003.

Changes:
 * Added Support for third-party themes
 * Finale fixes on security
 * Added DirectX 9.0 and above Support
 * Added GameLib 1.0 (By GameOS)

Not even leaked
 * Added more features to cmd

Home/Professional
Bonus release of Windows 2003 for Home and Office users

Changes for Home Edition: Changes for Professional Edition: Removed Content Not even leaked
 * Removed some features for cmd
 * Added Windows Media Center
 * Limited Firewall
 * Added new account type: Pre-Administrator
 * Improved Firewall, security
 * Added Configure your server
 * Removed support for DirectX 7.0, by adding GameLib 1.1 (By GameOS)
 * Removed Windows Media Player 9.0, by replacing Windows Media Player 10
 * new Update website : msws://update.win2003.microsoft.com)

Support
Mainstream ended on July 12, 2010. Extended support ended on July 13, 2015.

Trivia

 * Earlier this OS is meant to be Home Editon of Windows 2000 but canceled and changed to Windows 2003.
 * There is a secret theme named "SmallAeroTest", maybe this is an Aero support test for 128 MB Cards.
 * It meant to release on late 2002, but there are some problems with releases, release begin longer, and longer, and has been released in 10.04.2003
 * It meant to release Service Packs, but no SP is released. Source "Microsoft Plans of 2004-2007"
 * BTW, Service Pack 1 Beta 1 and 2 are only released Service Packs Ever. Official SP 1 Beta 1(3098.03sp.beta1-1130.030611-2311), Official SP 2 Beta 2(3098.03sp.beta2-1623.030730-1140)

Best updates for Windows 2003

 * KB030501 - Security Update (For Final, 01.05.2003)
 * KB061111 - Windows Defender Install Update (For Final, Professional/Home, 11.11.2006)
 * KB091011 - Internet Explorer Update 8.0 (10.11.2009)
 * KB050505 - Windows LDDM/WDDM Driver package (05.05.05)
 * KB050605 - Windows Aero (Fully working from Vista Beta 2 - 06.05.05)
 * KB100101 - Final Technical update for all editions of Windows 2003 (01.01.2010)

Between Longhorn and 2003.
There are rumors, it meant to be some elements, or all project has to be moved to 2003.

Only one file exists from longhorn. From 3683 sidebar.dll (Made 01.01.20039)