You need to create seperate identities. Look in OE Help under 'identities' Each identity can be password protected for privacy.
Setting up multiple identities
If there is more than one person in your house using the same computer for e-mail, each person can have a separate mailbox in Outlook Express. This means that each person can have separate messages, contacts, and personal settings. This is made possible through the creation of multiple identities. Once the identities are created, you can switch among them without having to shut down your computer or lose your Internet connection.
The following topics provide more information:
Add a new identity
Delete an identity
Switch to a different identity
Change the current identity's setting