However,
you have an option in Office 2007 to save the files with in older files
extensions, But if you are frequently using the older versions of the
file and also if the files created by you are to be shared on other
computers which have earlier versions of Office, you may want to save
all your new documents in the older format, but that would create
duplicate files. There is better option in Office 2007
applications to change the default saving file format to the older
format and then the new file format in Office 2007 will be changed to
.doc, .xls and .ppt for Word, Excel and PowerPoint respectively.
Today we will set the older file format for Word 2007 and other
applications will be discussed in the next tips. Follow the given steps
to set the default older file format for Word 2007:
First click on Start button, go to Program then click
on Microsoft Word 2007 to run the word application.
Now click on File menu in the top left
corner then click on
Word
Options
button
to change the default word options.

In the left side panel, click on Save
option, and now "Customized how documents are saved" option will appear
in right side panel.

Here find the "Save File in this
format" option and click on drop down box to select the different
format. Now you will find many options here, select the
Word 97-2003 Document (*doc) option.

Now click on Ok button to save the settings and all new Word files will
be created in the format you set as default.