[JackalsNose]

Of course everyone is familiar with the several different IM clients: Trillian, AIM, etc

My personal favorite is pidgin. The client is not headed with an ad like AIM and it does not have the bloatedness of Trillian. Personally, I've had a problem with the windows version of Pidgin only in that the spell check isn't working. I know it's a luxury, but I got accustomed to it in Ubuntu (which,in appearance, it looks better in as well)

You won't have to worry about the client inserting itself into your start-up processes, and it is very simple to utilize Buddy Pounces to message your favorite buddies as soon as they sign on. Logging is a very nice feature and organizing buddies by log size keeps your most talkative friends at the top of your list. You could also organize manually, but this would take too long for people with sizable buddy lists.

It's also pretty nice to have the ability to open up a new IM windows with Ctrl+M. Setting up escape as the close shortcut (in ubuntu pidgin) made my conversations in class much easier to conceal.