Re: IT support can make strong people cry.
I would tell them why it was not a good idea to have 42GB of file on the desktop and give them training on how to MOVE it to the appropriate folder and then create a shortcut for it on the desktop.
Back in the days when Macs were uber-secure.. I visited a mate and noticed just how long his machine took to start. And saw how cluttered his desktop was. At home that night I got him on ICQ, got his IP, ssh'd in (without needing username or password or having some defaults, can't recall which - whatever it was it was different to what he used himself), and started running some scripts to make folders and move stuff. He noticed his machine seemed a bit busy (IIRC for some reason on the Mac's it wasn't a case of just moving pointers, but I may've been spreading stuff over different disks with shortcuts to the original location). At the end suggested he restart his machine then we could talk about a security issue. He was amazed at how quickly it started when it didn't have to try and draw many thousands of icons on the desktop!
Wish I could've seen his face when I told him how, armed with his IP (he was on dial up so no router) I could get into his machine without knowing his username or password, and have full control over his data. I did talk him through how to block SSH at the firewall and how to open a terminal and change a few things so it was secure.