Export Outlook Express 5

Do you know where the mailbox file is kept for Outlook Express (version 5)? I’m trying to move it from an old Windows 2000 boot partition to another W2K partition and would like to preserve its contents. Is there a way of exporting its contents into another file and then importing that file in my other partition? Outlook Express has an export function but it exports
directly to Microsoft Outlook in the current partition. Thanks in advance for any help given.