Asking if I want to set Outlook Express as my Default

[TRM]

I'm running Outlook 2003 and Outlook Express 6.0. How do I get the question
to come up each time I open Outlook Express "Outlook Express is not your
default mail program. Would you like to set it as your default"? I set no to
this and asked it not to ask me that question again. I have since found out
that I would like this question asked. How do I reset it so that I'm asked
that question each time I open Express 6.0.

Thanks