An acronym for the Original Equipment Manufacturer's Preinstallation Kit. A collection of tools, scripts, samples and documentation given to anyone who purchases an OS from a Microsoft Authorized Replicator in bulk for eventual sale to a 3rd party consumer or business.

The OPK is re-released for each revision of the Operating System, with tools and technologies that are specific to that release.

The Windows XP OPK release CD contains 1/2 a dozen tools for both the x86 and IA64 platforms, most of which are peripheral to the preinstallation process that is principally provided by:

Sysprep.exe -- in the \tools\\ directory
Factory.exe -- in \tools\\, provides application preinstallation and cleanup functionality.
setupmgr.exe -- in the \wizard\ directory, a tool for producing Unattended installation deployment shares.
mkimg.cmd-- in \winpe\, a script that allows you to build your own customizeable WinPE disc

The OPK documentation (and the most valuable part of each release) is available in:

For more esoteric deployment problems consult the whitepapers available in:

The Windows XP OPK CD is also a bootable WinPE disc.