Outlook 2000 Question

My dad is running Windows 98SE with Office 2000, He had Adelphia cable which allows him muliple e-mail addresses. Of he uses outlook express I can configure his e-mail properly for each account but for the Outlook 2000 I can’t get the accounts to be separate. I have tried setting up all the users in windows 98SE, then linking them thought outlook but I still get all the accounts e-mail in one. Not sure what I am missing.