Multiple Desktops & Outlook Mailboxes

I recently upgraded to XP Home and installed Office XP
Small Business Outlook. I set up four desktops in XP and
entered each one and set up an Outlook mailbox for each
user within their desktop. Now who ever is logged into
Outlook, receives everyone's mail and can delete
everyone's mail. It is like the server can't decide which
mailbox to do put it in so it gets put in all. Each
desktop has only one mailbox it it. I am currently
operating off a cable model and router.