URGENT HELP RECOVER ADDRESS BOOK

Hello,
Hi, can anyone help me, my pc was using by more than 1 user a/c and all a/cs having outlook express seperately now pc is not such position and i must have to formate the pc after taking backup. now i dont know how to take outlook express address book backup. where it stores. i know only 1 file web address book is with program files\ outlook folder.
can anyone help.