Implement webview.

The vista+ way, and the XP way for showing details both use the undocumented XML/XAML-based DirectUI interface. Webview, however, uses documented interfaces that have existed since at least Windows 98. Webview is also easily customizable by editing or replacing the HTML files. Another advantage of Webview is that, because it is not an explorer bar, the navigation pane can be viewed simultaneously with Webview.
The details of a file, such as size, and a preview image of a file, are not things that should be in a toolbar, and the ability to view these things in explorer has been a standard feature in Windows since Windows 98.