I know how to disable system tray icons.
But what I want to know is how to make specific icons in the system tray disappear such as kazaa, edonkey and edonkey bot.

I have found that they are removed by way of
the "Startup" tab in the "System Configuration Utility". To open this, click START, then RUN,
then type: msconfig , then click OK.
Find the the "Startup Item" that you want to
dispose of, and uncheck its box, and click OK.
USE CAUTION. Item names are not in plain language. For example: If you want to get rid of
the gray Desktop Icon that is always on top of all your programs, then uncheck "WksSb".

NOW, every time you start your computer, a dialoge box will appear saying that you have made changes to your computer. SO, in it, check the box for "Do not tell me again" (or what ever it said).

You can also disable some of them manually from the program. For example, in Kazaa you can tell it NOT to start when Windows starts. I'm not sure about eDonkey.