When I tear apart someone's laptop, I like to take photos of the parts
of the laptop scattered all over my workbench. Showing the customer a
photo of their precious machine in pieces somehow enhances my ability
to charge a fair amount for the time and effort involved.
Another fun trick is do a screen capture of the normal desktop, and
save it as a JPG file. I use this captured picture as the wallpaper
image. In XP, right click on the desktop, select "Arrange Icons By",
and uncheck "Show Desktop Icons'. When the user tries to do something
on their desktop with the mouse, nothing happens.