Microsoft Office 2007 Compatibility Pack
Open, edit, and save documents, workbooks, and presentations in the file formats new to Microsoft Office Word, Excel, and PowerPoint 2007, after you install this compatibility pack. That is to say, you can open Office 2007 documents in Office 2003.
Download it.
http://www.microsoft.com/downloads/details.aspx?familyid=941B3470-3AE9-4AEE-8F43-C6BB74CD1466&displaylang=en