How to backup+restore address book Outlook (Express)?

[msoff20xx]

Assume I want to backup the current address book of my Outlook and restore it later (possibly to another version).

How can I do this ?

Again: I don't want to care about the current version

- Outlook vs Outlook Express

- Outlook 2003 vs Outlook 2007

- Outlook 32bit vs Outlook 64bit

I would like to have a convenient transparent way of interchanging the address books?

Is there a 3rd party tool for that?

Peter