This tip will help you to resolve the compatibility issues between the Microsoft Office 2003 and Office 2007
because all programs in MS office 2003 used the old file extensions for its different programs. For example Word 2003 saved files with extension .doc, Excel 2003 with .xls and PowerPoint with .ppt but on the other MS office 2007 used the new file extensions for its different programs.Word 2007 saved files with extension .docx, Excel 2007 with .xlsx and PowerPoint with .pptx.
Now the problem is that when you will try to open office 2007 files into office 2003 and you will not open the file due to compatibility issues between both office versions. Microsoft provides a free compatibility pack to convert office 2007 documents to the office 2003 format. There are many third party free converter are available but here we are using Microsoft office compatibility pack.
Copy Paste Link in your address bar and Press Enter And Download this Converter Pack
http://www.microsoft.com/downloads/en/details.aspx?FamilyId=941b3470-3ae9-4aee-8f43-c6bb74cd1466&displaylang=en