Recently, my colleage Pierre pointed me to this extension for Office 2007: UBitMenu.
It restores the classic menu structure of Office 2007 on top of the Office 2007 ribbon.
In the meantime, I got used to the ribbon navigation, it really has advantages, but sometimes it would be nice to have the previous menus if you can’t find a certain functionality you don’t use very often. Microsoft also offers the interactive command references to help you out.
The tool is free for personal use.