how to Open folders in Windows Explorer mode by default (i.e. with folder pane enabled)?

Open folders in Windows Explorer mode by default (i.e. with folder pane enabled)

When you double-click a folder, it opens the folder Window without the Explorer bar enabled (default setting). When you right-click on the folder and choose Explore, it does. To set Explore as the default action, follow these steps:
1. Open My Computer window.
2. Click Tools, Folder Options, then click File Types.
3. From the list, locate the entry FOLDER with extension of (NONE).
4. Click Advanced, select Explore, then Set Default
5. Click OK and close the dialog.

To accomplish this via the Registry:
1. Open Regedit.exe and navigate to:
HKEY_CLASSES_ROOT\Folder\shell
2. In the right pane, set the value of (default) to explore