If you can believe it, Windows Live Messenger (formerly MSN Messenger, formerly Windows Messenger) is 12 years old; it had its initial launch on 12 July 1999.
Amazingly, really old versions of the Messenger app still work with the service to this day. The versions seen in the video below are 4.7 and 5.0.
Note to XP users: You can use MSN Messenger 4.7 which is built-in to the XP OS, however it is feature-limited and by default the service that allows it to run is disabled, so you have to manually enable the .NET and “Messenger” service for it to work. Also if you have an XP where there is no .NET updates on it, it won’t work at all because it requires those services to run.
Additional note: I do not know whether Windows Messenger is in the Home Edition of XP, but it is in the Professional Edition.