Microsoft Download Center Office Document Open Confirmation Tool page contains the following overview:
Microsoft has released a tool that will require confirmation before opening Office 97 and Office 2000 documents (Word, Excel, PowerPoint, or Access) launched from within Internet Explorer. By default, Internet Explorer issues a security warning before launching unknown applications and files, allowing users to choose not to open them. This tool gives users the option to treat Office documents in the same way, preventing them from automatically opening when a user clicks on a link to an Office document, or browses to a Web page that hosts an Office document.
Note This update is applicable to all languages supported by Office.