Have Office 2007 or 2010? Have friends or colleagues with Office 2003? You can't open Office 2007 or higher files in Office 2003 without downloading a compatibility pack, but there's a very easy solution. Just save your 2007 projects as 97-2003 files. Go to the Office button and click "Save as". See the example from Word 2007 below. It's as easy as that. The file will be saved with an extension (.doc, .xls, etc) that Office 97-2003 will recognize and accept. Now you can send files you've created in a new version of Office to friends who are still using older versions.
