If you should need to re-install your system, you typically have to re- install the latest version of Internet Explorer 3.x and it's companions, Internet Mail & News. Most of the time this means re-typing your e-mail addresses, which, for some, could prove to be time consuming and laborious. For NT 4 users the complete address book file is located in "%SystemRoot%\username.wab." You can move this file to wherever you want to keep it (say a partition that never gets deleted, or back it up on floppy). Then, edit the following key of the registry to point to the correct location:
HKCU, Software, Microsoft, WAB, Wab File Name
I would guess that the same file is contained the Windows root directory for 9x users and the registry key would be the same.
Thanks to WinInfo subscriber Brian Kelley for the tip