niko
I use most of them and as long as you are prudent in the filesharing part of the program, they are a great communications tool.
I use a program called Trillian which is one interface capable of accessing all of the popular Instant Messaging programs in one interface.
By using Trillian, I no longer have to have 4 or 5 IM programs. It does them all.
http://www.trillian.cc/learn/ I'm using the free version. There is also a Pro version available.