Outlook and NEW Xp

Received a new laptop with XP already installed. Installed OL and put the new pc in place of the old WIN 98 Pc. Assumed OL would see the old mail box and data however it does not. I get new mail but can’t see the old mail. Would like to understand why and how to avoid as I need to repeat this process. As well as get old mail from WIN 98 to the new XP. WIN NT NOS