Word 2010 is opening my word 2003 attachments

I normally use Word 2003 for documents, although I use Outlook 2010. This morning I opened a Word 2010 document and after quite a while of some sort of an installation, I was able to open the Word 2010 document. I did not think too much of it, except that later I was sending an e-mail and attached a Word 2003 document and when I went to check it (i.e. open it up) it opened in Word 2010. How do I disable Word 2010 as my default program to open Word documents. I do not want to uninstall the program, but at this point I am not ready to learn how to use Word 2010.

Thank you for the suggestion, but I already tried to do that. I even got more specific. Within Default Programs I used the approach of "associating a file type (in this case doc.) with the program, but the only program I could use was Microsoft Office (or Word) 2010. Even though I use Word 2003, for some reason the computer now is overriding that and only allowing me to open these e-mail attachments with Word 2010.