Tried Celeste's solution, but it transfers not just the address book, but also any emails, tasks, etc from the source version of Outlook, overwriting those previously held in the destination version. Thanks for the tip though, this is handy to know for backup purposes.
Skip's solution sounds like a definite possibily, but I have no idea what type of file I should create in order that Outlook will read the addresses correctly when it imports it to the destination file.
Any thoughts anyone?