Outlook does not use an address book. All your data is in one file.
Nor should you export or import Outlook data.
The file you need is your Personal Folders file (*.pst) It's where all the
mail, calendar, contacts etc are stored.

Take a look at these pages for info on Outlook data backup or transfer:
http://www.slipstick.com/config/backup.htm
http://www.howto-outlook.com/Howto/backupandrestore.htm
http://office.microsoft.com/en-us/assistance/HA010771141033.aspx