Microsoft provides free Office Compatibility Pack for automatic conversion of Office 2007 documents to Office 2003 format, the small 28 MB compatibility pack enables earlier version of Microsoft Office to Open, Edit & Save Microsoft Office 2007 Documents.
However, the newer Office 2007 file format might not be the best way to distribute your files, Microsoft therefore provides free Office 2007 add-in for conversion and publishing of Office documents into more popular and widely used Adobe Acrobat PDF file format.