I want to be able to double-click on a DOC file in explorer and have it open in Word 2003

AND

I want to be able to double-click on a DOCX file in explorer and have it open in Word 2007



Background Info:

I have Word 2003 and Word 2007 installed on my PC.

At the moment when I double-click on any word file from explorer (DOC or DOCX) they open in Word 2003 by default.

If I want to open a DOCX in Word 2003 I have to do it from inside the Word 2007 programme.

I have tried setting the default programmes but it always reverts to 2003


In short - how do I get DOC to open in 2003 and DOCX to open in 2007 - automatically.

Thanks in advance