How can I be certain I have legitimate Microsoft software if it came preinstalled on my computer's hard disk?

From Microsoft Outlook 2002 Help
Microsoft licenses many personal computer system manufacturers to preinstall system software directly on the hard disks of their computers for sale. In some instances, computer manufacturers are also licensed to preinstall specific application software on the hard disk. These titles can include system software such as Microsoft Windows 2000 and server software such as Microsoft Windows NT Server, as well as applications such as Microsoft Works.


For Microsoft software, the computer manufacturers must include inside the computer box an End-User License Agreement (EULA) either in the documentation or online within the software, and, for system software and most applications, a Certificate of Authenticity either in the documentation or as a label applied to the computer. In most instances, computer manufacturers also include manual(s) and a set of software disks or a CD-ROM. Microsoft branded OEM operating system CD-ROMs include, edge-to-edge holograms.