[keith_d]

Here's my list, in order:

0) Take a screenshot of their current display and rotate it 180 degrees it for later use
1) Set high contrast, stickykeys and swap mouse buttons
2) Change system sounds to one of the wierdo sets
3) Change the screensaver to display the screenshot from step 0
4) Invert display. Note that when the screensaver comes up it'll look normal - until they press a key
5) Sticky tape on the mouse
6) Plug your cordless mouse into the back of their PC and move their cursor around whenever they move their now useless mouse.

7) remember to lock your own PC every day for the next six months