Most Windows users are familiar with MSN Live Messenger, which they call "the chat program" (not accurate technically speaking because MSN Messenger is an instant messaging (IM) service, not a chat). They believe that it is the only way you have to communicate with friends who are away if you do not have Skype.
However, thanks to the proliferation of botnets and MSN viruses, Windows users might have noticed how their sessions with MSN are plagued by unwanted messages ("See this video", "click here for an offer", blah, blah) and by unreliable log in time.
When I migrated to Linux, one of the first things I discovered was that you can keep using MSN Live although you are not running Windows. You do it with one of the many Linux IM clients...and the beauty is that you do not get the problems that are associated to MSN Live Messenger. You have to learn to compromise, though, as their functionalities are different.
This program is an MSN Live Messenger clone. It can enable video calls, but not conferencing. For those who like IM with a cam, this is a good option. I have tried it from Mandriva to Mepis (Linux-Linux) and it works. The cam feature does not seem to work from Mandriva to Windows, but it is OK with me because I was never fond of the video cam sessions anyway. As MSN Live Messenger, this IM client works only using MSN network. That might seem obvious, but I said it because most Windows users think that they need an independent program for each different account they have. So, most Windows users have a program for MSN, Skype, etc.
This is the default IM client in KDE. This Linux program is simple and supports many more accounts. One interesting feature is that this little program lets you know when one of your MSN contacts is in invisible mode: that's right, no hiding from the eye of Sauron. The problems: no video.
This is a simple but extremely powerful IM client. Because of the possibility to extend its functionalities, this IM program can control your MSN, Yahoo, and even your Skype account without any hassle. Yes, you log in and you can communicate with all of your friends and contacts with this little thing. It also has a fun feature called "psychic mode" that lets you know some seconds in advance when one of your contacts is typing a message for you before he or she sends it (you read something like "You perceive a disturbance in the force").
This program can also run in Windows. Again, it does not support video but for that's fine with me because I like IM to be fast and reliable. Video is a nice add on, but not an indispensable one for communication.
As I said, the IM experience in Linux can be a little different if you learn to compromise: there are features that you don't get, but there are many others that you were not even aware of and that might enrich your IM sessions, such as data encryption, effects, plugins, etc.