Windows Server 2003

Windows Server 2003 is the server counterpart of Windows XP. It comes in editions like Datacenter, Web Server, Standard, Enterprise and Small Business (the latter is technically a separate version). It replaces Windows 2000 Server and was replaced by Windows Server 2008.

It is the last version of Windows Server to support computers without ACPI and the last version of Windows to use NTLDR to boot the system.

Release 2
An interim release under the name of Windows Server 2003 R2 was released to manufacturing on 6 December 2005.

Other versions
As well as the standard Windows Server 2003, several other editions were built on the NT 5.2 kernel, including Storage Server 2003 (released on 10 September 2003), Storage Server 2003 R2 (released on 6 March 2006), Compute Cluster Server 2003 (released on 9 June 2006), Small Business Server 2003 R2 (released on 1 September 2006) and Unified Data Storage Server 2003 (released on 5 December 2006).

Startup sound
There's a widespread misconception that this startup sound from a promotion animation (cut by TheCanadianToast) is used for a version of Windows Server 2003 for the United Kingdom. However, no country-specific edition of Windows was ever made until Microsoft was forced to make N and KN variants for Europe and South Korea respectively which removes Windows Media Player and other features due to antitrust lawsuits; Windows didn't have English (United Kingdom) as a display language option until Windows 8/Server 2012. All versions and localizations of Windows Server 2003 use the Windows XP startup sound.

Source code leak
On 23 September 2020, the source code for Windows XP Service Pack 1 and Windows Server 2003's RTM build leaked on 4chan's /g/ board. As mentioned on the original post, the code had been circulating in private circles for several years at most. Due to the incompleteness of both source code repositories, primarily within the activation functionalities, it is fair to assume that the disclosure had originated from a Microsoft Partner who had access to the source code rather than Microsoft themselves. The ability to glance into the groundwork of this operating system has led to some discoveries, an example being the checks for enabling the DirectUI-based Start Page from  being usable in build 2410.