Saving backward-compatible files within Office 2007
When you select Save within Word, Excel, or PowerPoint 2007, your file will be saved in a new Open XML format by default. A Microsoft Word 2007 file, for
instance, will have the DOCX extension. Luckily, Microsoft Office 2000 and 2003 can open the new file formats after you install a Compatibility Pack update (see the next page
However, Office applications that preceded version 2000 won't open Office 2007 files at all, nor will most third-party productivity software that opens older Microsoft files. What if you need to share that DOCX file with someone running an older version of Word? Or what if you use a third-party application, such as Corel WordPerfect 12 or the Web-based Google Docs, that can only read Word's older DOC format?
The Microsoft Office button in the upper left corner of the 2007 applications lets you check for file compatibility and save backward-compatible versions of your work.
The best bet for making files from Office 2007 compatible with older (or rival) Office software is to save your work in an older file format. This is especially true while Office 2007 is new, because the majority of
Office users aren't likely to upgrade immediately, so they'll continue to use
the older software and file formats.
To save backward-compatible work using Word, Excel, or PowerPoint 2007, make sure to click the Office button and choose Save As--not Save--from the pull-down menu. Then you can choose to save work in the DOC file format that older versions (from 1997 to 2003) of Microsoft Word can open.
Before you save a file, it's also a good idea to select Prepare from the Office button and run a Compatibility Checker. This process will show how the file might change when it's opened in earlier versions of Office.