A way to keep what I Dl from other users on putor?

Hi

I am the admin on my computor, but it has 3 other "users ". Things I install, download and use seem to show up on their desktops as well. Most is not a problem, like Spybot, but when they sign in "my" icq pops up, as do most things I downloaded.
Their login is password protected and I wish to respect that, but on other hand don't want all I do or download showing up on their desktop. Plus some of it hinders them as they are unsure why these things are starting up when they log in. Is there a way to keep what I download only on *my* desktop? What is the point of differant users/Admin if my dl's put icons on their desktop too? Any help and advice would be greatly appreciated!