From AIA blog

Microsoft is keep on releasing new versions of Office with new features.So corporates will buy and use the latest versions of MS office.

But you have personally Office 2007 and you own only office 2003.If You have files such as .docx,.docm which you created in Office 2007 and you want to edit it ,but you have only Office 2003 installed on your machine.

Don't worry.There is a way.

Just download the Compatibility pack for the 2007 Office Word,Excel and Powerpoint from Microsoft and install it.
Afterthis you will be able to read,edit the documents created in newer versions of MS office.

You can download the compatibility pack from here:
Download Compatibility Pack from Microsoft


Alternatively you can use a conversion tool,to convert between doc and docx and various other formats

For that purpose use the tool from the below link
Convert To/From Word Files