If you have already using Microsoft Office 2007 for Windows or Microsoft Office 2008 for Mac and save the documents in Office Open XML file format (with the file extensions such as .docx, .xlsx and .pptx), you probably will face incompatibility issue and non-support of OpenXML format in other applications including of Microsoft own older version of Office software for Mac platform, i.e. Microsoft Office 2004 for Mac and Microsoft Office v. X for Mac.
Previously, if you intend to port and move the Office documents created in Office 2007 for Windows or Office 2008 for Mac native Open XML format to your MacBook, iMac, Mac mini or Mac Pro running Mac OS X with Mac Office 2004 and Mac Office v. X, you would have to rely on the workarounds to be able to open, view or edit Office 2007 or Office 2008 files on Mac. Microsoft has now released a converter that is dubbed Microsoft Office Open XML File Format Converter for Mac, now at version 1.2.1.
The converter provides Mac users running older versions of Office who receive new Office 2007 or Office 2008 Open XML documents a way to open and read the files. Microsoft Office Open XML File Format Converter for Mac is a stand-alone Macintosh application that converts Office Open XML files to rich text format (RTF) files that are compatible and can be automatically opened with Microsoft Office 2004 for Mac and Microsoft Office v. X for Mac.
The converter currently only able to convert Word Document (*.docx) and Word Macro-Enabled Document (*.docm) format documents to RTF documents. Open XML Converter can convert Word documents, Excel workbooks, and PowerPoint presentations to RTF documents. Users can choose to convert and open one file, or convert a large number of files.