Thanks Wade & Jacob for the heads up on this one. Seems Microsoft have released Windows messenger for Windows XP v4.5 build 0127 via Winupdate this time. When I tried to get it of the MSN site it was still 0125. So I am not sure if this is available for other Windows versions.
Windows Messenger lets you see when your friends, family and colleagues are online, send an instant message, send a file, have a voice chat or a video conversation, and engage in other collaborative efforts. Now, you can even make phone calls from your computer to a phone almost everywhere in the world for a very low rate using the service provider you choose. Windows Messenger is easy to use, delivers great voice and video quality, and enables cool, new innovation with lots of other products and services you use every day
Download: Windows XP Update Site 952 KB,