Brutus,
Here are some new features of Windows Messenger 5.1 copied from
http://www.windowsitpro.com/Windows/Article/ArticleID/44884/44884.html
Q. What's new in Microsoft Windows Messenger 5.1?
A. New features in Windows Messenger 5.1 include
a.. improvements in file-transfer functionality for users who have
multiple network connections (e.g., configurations involving wired and
wireless network connections, users of VPN connections)
b.. improvements in Windows XP Tablet PC Edition 2005 and laptop support;
specifically, improved support for onscreen stylus writing and better
performance when using power-saving features such as standby or hibernation
in portable computers
c.. improvements to presence integration with applications, including
better presence integration when applications are in full-screen mode (to
avoid unwelcome instant messaging--IM--interruptions) and quicker refresh of
presence information in applications such as Microsoft Office Outlook 2003,
Microsoft Outlook XP, and Microsoft SharePoint Portal Server services
d.. improvements to the sign-on process, enabling a quicker sign-on
e.. support for Microsoft Office Live Communications Server 2005
federation and advanced architecture features
