This article describes an update that enables you to update Windows 8 or Windows RT to Windows 8.1 or Windows 8.1 RT when Windows 8.1 and Windows 8.1 RT are released in the Windows Store.



Additionally, this update fixes several issues in Windows 8 Enterprise, Windows Server 2012, and volume licensed installations of Windows 8.



Note You cannot update to Windows 8.1 Enterprise, Windows Server 2012 R2, or volume licensed installations of Windows 8.1 from the Windows Store.

 

http://support.microsoft.com/default.aspx?scid=kb;en-us;2871389

 

Daniel