If you are working in an environment where some users have shifted to Microsoft Office 2007 (or Office 2012) while the rest are still using the older version Office 2003, the following Compatibility Mode trick will simplify things for you.
The problem is that Word 2007 will switch ON Compatibility Mode only when you open a document created in previous version of Word.
To force Compatibility Mode in Word 2007 for even new documents, you may add the CompatMode key to the registry as explained here:
Open the Registry Editor in Windows (Windows -> Run -> RegEdit) and search for the following key in the registry (use Ctrl + F):
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Word\Options
In the right panel, right-click and choose New - DWord. Replace New Value #1 with CompatMode
Double-click CompatMode, and replace the 0 with a 1. Close the registry, then start Word. All document will be editable in compatibility mode now.
You should save the files as .doc, not .docx format as it is not supported by Word 2003. Similar registry settings for Compatibility mode maybe used with Excel and PowerPoint 2007.
Realted: Use Office 2007 Files Without Upgrading Microsoft Office
What is Compatibility mode in Microsoft Office ?
When you open a document in Microsoft Office Word 2007 that was created in Word 2003, you'll see Compatibility Mode written in the title bar of the document window. Compatibility Mode ensures you can open, edit, and save Word 97–2003 documents using Word 2007 but no new features in Word 2007 are available so that people who are using previous versions of Word will have full editing capabilities.The problem is that Word 2007 will switch ON Compatibility Mode only when you open a document created in previous version of Word.
To force Compatibility Mode in Word 2007 for even new documents, you may add the CompatMode key to the registry as explained here:
Open the Registry Editor in Windows (Windows -> Run -> RegEdit) and search for the following key in the registry (use Ctrl + F):
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Word\Options
In the right panel, right-click and choose New - DWord. Replace New Value #1 with CompatMode
Double-click CompatMode, and replace the 0 with a 1. Close the registry, then start Word. All document will be editable in compatibility mode now.
You should save the files as .doc, not .docx format as it is not supported by Word 2003. Similar registry settings for Compatibility mode maybe used with Excel and PowerPoint 2007.
Realted: Use Office 2007 Files Without Upgrading Microsoft Office