Outlook Logon Credentials

I have computers running Windows 2000 and 98 with Outlook 2000. Every time we connect to the Exchange server we get prompted with the Enter Password box. I have one computer with Windows 98 on it that saves the User Name and Domain Name info in the fields so that all the user has to enter is his password. I can?t figure out what is configured differently on his computer to let him do this. How can I get everyone?s computer to do this? Thanks.