If your users have Windows 98 or Windows 2000, they are probably using the "Web Desktop" style interface. IE4 users can also turn this interface on on earlier versions of Windows, too. If you look at their desktop, you'll see on their task bar there is a "Quick Launch" area. By default, the area contains tiny icons for IE4, Outlook Express, View Channels, and Show Desktop.
What if you want to add your own icons in this area? It is actually quite simple. Just create a shortcut or other program file in the correct directory. Where is that? It depends. IF %WINDOWS% is the Windows directory, and user profiles are off (Windows 95/98), look in:
%WINDOWS%\application data\microsoft\internet explorer\quick launch
If you use user profiles under Windows 95 or 98, or you are installing on NT/2000,
you'll be in: %WINDOWS%\Profiles\%USER%\Application
Data\Microsoft\Internet Explorer\quick launch
Where %USER%, of course, is the current user. The name of the file, without any extension, becomes the pop-up help balloon for the file. It is a simple matter to make your installation program set these up so that your own programs can appear here. Probably a good idea to ask the user first, of course.
How do you create a shortcut file? Well, that's another tip for a later day. You can find information about this in my upcoming Windows 2000 System Programming Black Book or Look up the IShellLink interface (hint: use CoCreateInstance to create CLSID_ShellLink).