Are you sure it's and ODT file? A Web search on "Word 2003" ODT returns many hits for posts saying that the installation of the Sun ODF Plugin will provide the required functionality. See, for example:
http://www.windowsreference.com/ms-o...word-20072003/
http://www.life123.com/technology/fi...-to-word.shtml
http://www.ehow.com/how_6951443_open...fice-2003.html
The main alternatives are:
• install the Open Office suite; or
• get whoever sent you the file to re-send it in one of the many other file formats supported by Word (eg doc, rtf).