The Plus! Extension is a software that adds functionalities to the Microsoft Windows Messenger (also known as MSN Messenger) chat program. It is very easy to install it, as it is easy to uninstall it, so do not hesitate one second about trying it! The Messenger Plus! Extension works with Windows 95/98/Me and Windows NT4/2000/XP. It requires MSN Messenger or Windows Messenger, versions 3.6 to 4.6.