When you double-click on a folder, it opens showing the contents in a window. To have your folders open in an Explorer view instead, and have their directory structures in the left pane, follow these steps:
1. Start Explorer 2. Select 'View->Options->File Types' from the menu 3. In the 'Registered File Types' Window scroll to the 'Folder' item 4. Highlight 'Folders' and select 'Edit' 5. Highlight 'Explorer' from the 'Actions' menu 6. Click on the 'Set Default' button
From now on, all your folders will open in Explorer.