In this case, Windows system files are present, so user data can be backed up from the installer using Notepad, before proceeding to install. This is done by pressing Shift + F10, inputting the path to the Notepad.exe in the System32 of the old Windows installation being replaced, using the File > Open menu to launch File Picker, and copying files from the old Windows to an external HDD connected while installing Windows.in most cases its best to format but you may want to get into the system in order to copy/ save files before doing a format later