Microsoft has been quick to explain why the holographic image on the face of the Windows Vista DVD includes a microscopic picture of three men who just so happen to be members of the team who worked on the Windows Vista DVD hologram design. Microsoft's Anti-Piracy Team designed a counterfeit-resistant digital "watermark" for the non-encoded surface of Windows Vista DVDs. Multiple images are contained in the hologram design, all of whose inclusion serves to make it more difficult to replicate a Windows Vista DVD. The other images are of old master works of art that are in the public domain.
The images are less than 1mm in size and are not visible to the naked eye, so must be viewed using optical magnification. Their presence does not affect the contents of the DVD and these security measures were never intended to be impossible to find, but rather difficult to reproduce. While it's extremely difficult to replicate a holographic design in general, the inclusion of original images makes it that much more so.