Windows XP build 2428

Windows XP build 2428 is a pre-Beta 2 build of Windows XP. As of 2020, it's the earliest leaked build to drop the classic Windows flag used from Windows 3.1 to 2000 and replace it with the XP one (although many resources, such as the About banner and the safe to shutdown screen, still use the old flag). It's also the earliest leaked build to include a preliminary version of the Luna theme, which replaced the previously included Watercolor and Sample Test Visual Style themes.

Windows Product Activation also works and prevents logon after 14 days of installation, however Safe Mode with Command Prompt will bypass this and it can be disabled by setting the key  to 0.

Fast Facts
In the taskbar properties, you can see the luna theme, but it has the old Windows flag!