Word doesn’t accept outlook 2000 as a mail app

I’m running microsoft office 2000 and when I go into MS Word and hit the E-Mail button up top on the toolbar it auto sends me to Outlook Express does anybody have any solution? I’ve set it as a default at IE6 and I looked into Set Program Access and Defaults, and in XP Pro, it doesn’t give me the option of setting it to Outlook. I’m stumped somebody help me please.