Outlook Express data is stored in various locations. You can just copy the messages and address book over, while the email account settings and rules must be exported from the registry and then importing into their new location.

Messages

X:\Documents and Settings\[username]\Local Settings\Application Data\Identities\{[your-user-identity-number]}\Microsoft\Outlook Express

Address Book

X:\Documents and Settings\[username]\Application Data\Microsoft\Address Book\[username].wab

Email Accounts**

HKEY_CURRENT_USER\Software\Microsoft\Internet Account Manager\Accounts

Blocked senders lists and other mail rules **

HKEY_CURRENT_USER\Identities\{Identity Number}\Software\Microsoft\Outlook Express\5.0\

** X:\Documents and Settings\[username]\ntuser.dat