Exchanging files between Microsoft Office 2003/XP/2000 and Microsoft Office 2007 (or newer)
Microsoft has added new XML file formats to Microsoft Office Word, Excel, and PowerPoint 2007 to reduce file size and improve security and reliability. To help ensure that you can exchange documents between Microsoft Office releases, Microsoft has developed a Compatibility Pack for the Office Word, Office Excel, and Office PowerPoint 2007 File Formats.
