Outlook Express address book backup

Open Outlook Express
In 'File Menu' click 'Export' then click 'Address Book'
Click Text File (Comma Separated Values), and then click Export
Click the 'Browse' button and select where you want to save your Book
Type in a name for your Address Book and click 'Save'
Click 'Next' and check the boxes to select the fields you want to export
Click 'Finish'
You have backed up your Address Book

Import or restore outlook express address book

In 'File Menu' click 'Import' then click 'Other Address Book'
Click "Text File (Comma Separated Values)" and then click Import
Click 'Browse' to go to the location where you saved your book
Click the file name you typed in earlier
Click 'Open' and then Next
Check boxes to select the fields you want to import in the "Map the fields you wish to import" box and then click 'Finish'
If you receive a message "Would you like to replace the existing entry with the import entry?," click Yes To All to replace all duplicate entries
Close Outlook Express to finish.

Note: Better than just copying the address book *.wab file and more reliable.