Miranda IM is a multi-protocol instant messaging client for Windows. Very light on system resources and extremely fast, Miranda IM requires no installation and can be made to fit on a single floppy disk or USB drive. Featuring a powerful plugin-based framework and boasting over 350 plugins, Miranda IM is one of the most flexible and customisable messaging clients on the planet. To see how some of our users have customised Miranda IM, check out the screenshot section.
Protocol Support
+ AIM (AOL Instant Messenger)
+ Gadu-Gadu
+ IAX (Inter-Asterisk Exchange)
+ ICQ
+ IRC (Internet Relay Chat)
+ Jabber
+ MSN
+ Netsend
+ Tlen
+ Yahoo
+ And more...

Supported Operating Systems
+ Windows 95 / 98 / ME / NT / 2000 / 2003 / XP / Vista / 7

Bugfixes:
+ Fixed crash during NTLM authentication
+ Fixed possible crash in internal history viewer
+ Fixed Move to Group issue
+ AIM: Fixed crash issue
+ AIM: Contact lost custom name when moving to different group
+ Jabber: Fixed rare crashes
+ Jabber: Privacy lists were missing from the list editor
+ Jabber: Fixed options UI issues
+ Yahoo: Fix memory leaks.