With Vista, there are base requirements, minimum recommended requirements, and recommended requirements. The upgrade adviser will check to make sure you at least meet the bare minimum requirements, and based on your specs suggest a specific edition of Vista. If, for instance, your graphics card is lacking you may still get a green light and be able to run Vista, but not be able to 'unlock' the Aero interface in all of its graphical glory. Thus, given the various 'levels' of compatibility the exact version, adviser report, and system specs would be required to make an adequate review of Microsoft's assessment.

John