If you have a previous version of Windows (Windows 3.x, Windows for Workgroups) installed on your computer, and you want to run your installed applications from both the previous version of Windows and from Windows NT, then install Windows NT in the same directory as the previous version of Windows. This allows Windows NT to configure the Windows environment based on the existing environment and allows Windows NT to support the features of currently installed applications.
When the first logon occurs on the newly-installed Windows NT computer, the system migrates REG.DAT and portions of the WIN.INI file from the previous version of Windows to the Registry in Windows NT. The status of each step in the migration is recorded in the Application Log, which can be viewed with Event Viewer.
The first time each new user logs in, Windows NT presents a dialog box that lets him or her select the parts of the previous version of Windows to migrate into the Windows NT environment. The user can select whether to migrate the .INI files and/or the Program Manager .GRP files to the Registry. If the user cancels the dialog box and later would like to migrate the files, he or she must delete the following key from the Registry and then log off and log back into Windows NT:
HKEY_CURRENT_USER\Windows 3.1 Migration Status
Refer to Part IV, "Windows NT Registry," for information on the Registry and its entries.
Note The per-user dialog box and migration do not happen for the usernames Administrator, Guest, and System.
If a user chooses to migrate the .INI files, then each time he or she logs into Windows NT, the system reads the WIN.INI file and the SYSTEM.INI file and stores the information in the Registry. When the user logs off from Windows NT, the system updates the WIN.INI file and the SYSTEM.INI file with any changes made to the environment. This keeps the configuration of Windows NT and the previous version of Windows synchronized with each other.
If Windows NT is not installed in the same directory as the previous version of Windows, then configuration changes made under one version of Windows are not available to the other version. The same is true if the previous version of Windows is installed after Windows NT. In these situations, a user in Windows NT may not be able to run some applications installed under the previous version of Windows. The applications will have to be reinstalled under Windows NT (into the same directories into which they are installed under the previous version of Windows).
Regardless of where Windows NT is installed, changes made to the Desktop or to the arrangement of the Program Groups are not synchronized with the previous version of Windows.
Caution Setup installs TrueType font and font header files in SystemRoot\SYSTEM. Be careful not to delete the TrueType files from this directory. These files are used by Windows NT 32-bit applications as well as 16-bit applications. For more information on the TrueType font and font header files included with Windows NT, refer to Chapter 4, "Windows NT Files."