Here is another program that I really like. It isn't related to Computer Security, but it is still a really great program. You've probably heard of it, it's called Trillian.
Basically, with Trillian you can connect to multiple messengers and therefore you don't have to load all the regular messengers. You can connect to AIM, MSN, Yahoo, ICQ, and IRC. There are many reasons you may want to use Trillian instead. To start, the regular messengers take up way too much memory. Trillian takes up less memory then MSN, AIM or Yahoo. Imagine if you ran all of those at once just how much memory would be used. In addition, you can also sign onto multiple Yahoo/MSN/AIM/ICQ accounts with Trillian. You can't really sign onto two accounts at once with the regular messengers.
I still recommend keeping the regular messengers on your computer though. You can't use the Webcam feature with the free Trillian version. Trillian also doesn't have some of the games and other extras that come with the regular messengers. So it's good to keep the regular messengers around in case you need them. But I've been using Trillian for years though and highly recommend it.