Outlook 2003 – adding 2nd addres book

I’ve run into problems trying to add a second address book to Outlook 2003. Can’t find any literature on it.

In the address book, under Outlook Address Book I have my personal addresses in Contacts.

I have added another address book, MailingList, but cannot find a way to add the 600 addresses without them ending up in my Contacts book.

Can someone help?