SIM

There are lots of messaging programs which, using their popularity in operating systems like GNU/Linux, decide to go for other operating systems where there is already a clear dominating program like Windows Live Messenger for Windows.

SIM is an instant messaging client for Windows which will allow you to chat with your contacts in Windows Live, AIM, ICQ, Jabber, AOL or Yahoo! from one same messaging client, offering similar services to those offered by each of these protocols in their official clients.

It also incorporates a great number of extensions which will allow you to have extra functions which will make SIM a good opponent for the present available messaging clients.