Is Windows 8.1 Preview ready for everyone to try?
Are there risks to installing Windows 8.1 Preview?
What are the system requirements for Windows 8.1 Preview?
What languages is the preview available in?
Will my devices and programs work with Windows 8.1 Preview?
More here – http://windows.microsoft.com/en-gb/windows-8/preview-faq?ocid=W8_apps_help_tips