According to Mary Jo Foley from ZDNet, Microsoft has sent out the upgrade paths to close partners.
Users will be able to upgrade to Windows 8 (the name of the entry-level consumer version of the operating system) from Windows 7 Starter, Windows 7 Home Basic and Windows 7 Home Premium while maintaining their existing Windows settings, personal files and applications.
Users will be able to upgrade to Windows 8 Pro from Windows 7 Starter, Windows 7 Home Basic, Windows 7 Home Premium, Windows 7 Professional and Windows 7 Ultimate while maintaining their existing Windows settings, personal files and applications.
Users will be able to upgrade to Windows 8 Enterprise (available to volume licensees with Software Assurance contracts only) from Windows 7 Professional and Windows 7 Enterprise while maintaining their existing Windows settings, personal files and applications.
Users will be able to upgrade to Windows 8 from Windows Vista (without SP1 installed) but only personal files (meaning data only) will be maintained. If upgrading from Vista with SP1, personal data and system settings will be maintained.
Users will be able to upgrade to Windows 8 from Windows XP with Service Pack 3 or higher but only personal files/data only will be maintained.
source: Mary Jo Foley from ZDNet
