You can't add it to the actual window, but you can use a third-party addition like Messenger
Plus (http://www.msgplus.net) which will log your conversations and add a time/date stamp to
each.
____________________________________________
Jonathan Kay
Microsoft MVP - Windows Messenger/MSN Messenger
Associate Expert http://www.microsoft.com/windowsxp/expertzone/
Messenger Resources - http://messenger.jonathankay.com