: Even if a stolen or "grey market" key works initially, Microsoft can detect it and block it later, leaving you with a deactivated and limited system.

Windows Vista is proprietary software owned by Microsoft. Using unauthorized product keys violates:

Your data, privacy, and peace of mind are worth far more than a free key for an obsolete system.

For users with a valid Windows XP license, Microsoft offered a free or discounted upgrade to Windows Vista during its lifecycle.