This will back up your Address Book to your desktop. By default it chooses the desktop. If you want to change this, do a manual back up and choose a different location. Address Book should remember the next time. Double click on the back up to restore. Useful to put this action in front of any pseudoaction you may create that tampers with the Address Book database. (Requires UI scripting enabled.)
--Back Up Address Book
tell application "System Events"
tell process "Address Book"
tell menu bar 1
click menu item "Back up Address Book." of menu "File"
delay 3
keystroke return
end tell
end tell
end tell