I noticed the end-user license agreement for Microsoft software that is included with Windows Preinstallation Environment (Windows PE) 1.2 (eula.txt). In section "1. ELIGIBILITY." it states the following:
..."You may only install and use the SOFTWARE PRODUCT if you are an active Microsoft Software Assurance Member ("SAM") for the systems product pool or servers product pool, if you currently have license coverage for Microsoft Windows operating system (OS) Upgrades via a Campus Agreement or School Agreement, or if you are a current or former participant in the Windows XP Joint Development Program, Windows XP Rapid Adoption Program, Windows .NET Server Joint Development Program, or Windows .NET Server Rapid Adoption Program. If you do not meet one or more of the requirements listed above, you may not install or use this SOFTWARE PRODUCT and you must terminate the installation of this SOFTWARE PRODUCT immediately"...