Windows 10 is being released by Microsoft as a free upgrade for Windows 7 Service Pack 1 and Windows 8.1. The upgrade is being provided through a Windows Update and will be available at no charge for one year after the release date. Please note that Window 8 PCs will not get the free update unless they have been upgraded to Windows 8.1.
Due to the way the upgrade processes, some applications may be uninstalled prior to the upgrade. In theory, the process retains installation data and will re-install the application after the upgrade is complete. But if it is an application that is unfamiliar, that processes may not work. The end result could be a Windows 10 install with applications missing or miss-configured.
More specific information can be found here:
The update that provides access to the Windows 10 upgrade is KB3035583. With this update installed, a new folder will be created at “C:\Windows\System32\GWX” and the program GWX.exe will provide a prompt to reserve Windows 10 in advance of the July 29, 2015 release date. Once reserved, the Windows 10 update will download automatically once it has been released.
Mary Jo O'Neill