When Microsoft released Windows XP in 2001, deployment meant CD-ROMs, unattended text files (winnt.sif), and tools like Sysprep. The king of imaging was —a sector-based clone tool. WIM didn’t exist until Windows Vista’s development (2005–2006), when Microsoft needed a file-based, hardware-agnostic, single-instance image format.

Because of this, a "Windows XP WIM" is usually a custom creation used by system administrators for deployment tools like or System Center Configuration Manager (SCCM) to deploy XP on older hardware in enterprise environments.

imagex /info D:\xp_image.wim

In the world of enterprise IT and system deployment, two technologies seem like they belong to entirely different geological eras: (released in 2001, retired in 2014) and the Windows Imaging Format (WIM) (introduced with Windows Vista in 2006).

WIM uses LZX or XPRESS compression. A raw Windows XP partition might be 2 GB. Captured as a WIM file, it often shrinks to 600 MB – 900 MB.