Just spent 2 hours on phone with 4 different Microsoft Support Techs. Tried to upgrade from Windows 8 preview to windows 8 pro under Parallels 8. (not a Parallels problem) Will not install media center etc. components to Windows 8 Preview. Keeps saying Windows 8 already installed and bad activation code. 2 of the 4 techs at MS acknowledged it is a known problem, due to a bad link. 5th Level 2 tech will call me tomorrow with "fix". So if you're trying to upgrade from 8 release preview you may want to wait.