Adium is a free instant messaging application for Mac OS X that can connect to AIM, MSN, Jabber, Yahoo, and more. Learn more about Adium...
Adium 1.1.4 requires OS X 10.4.0 or greater.
If you're using OS X 10.3.9, you'll want Adium 1.0.6
If you're using OS X 10.2, you'll want Adium 0.89.1