With Office 2007, Microsoft has made changes to its file formats. The new file formats promise reduced file sizes, improved reliability, and enhanced integration between Office applications.
But this means documents created in Word 2007 and other Office components won't be compatible with earlier versions of Word (or other Office components).
To solve this problem, Microsoft has issued the Microsoft Office Compatibility Pack (Beta 2). It works with Word, Excel, and PowerPoint programs. In most cases, you can open, save, and create Office 2007 documents in earlier versions of the programs. The purpose is to allow users to exchange documents.
Getting Started with Microsoft Office Compatibility Pack
1. Install the latest Microsoft Office Updates
You will need the latest Office Service Packs to use the tool.
2. Download the Microsft Office Compatibility Pack
Follow the instructions to install O2007Cnv.exe.
Notes on the Microsoft Office Compatibility Pack
1. It will work with Office 2000, 2002/XP, and 2003.
2. It will help you open, save, and create documents in the 2007 formats.
3. It only works with Word, Excel, and PowerPoint.
4. With Office 2000, you can't create Excel and PowerPoint documents in the 2007 format.
For more information on the Microsoft Office Compatibility Pack, visit Microsoft's site.

