For the last few years I have been installing computers in people's houses - mainly Gateway and Dell. I've done something like 1200 since 2000, but...I will always remember one my first customers.
He was swapping an old word-processor with a state-of the-art high-end Gateway PC - 20" screen, wireless keyboard/mouse, laser printer, loads of RAM, fast processor, I was impressed.
We're supposed to a 20 minute demo to show them the salient points of the machine - like how to save/load files, how to boot/shutdown it down etc.
His first question kinda stopped me in my tracks: he picked up the mouse and said "what's this?"
Quick as a flash I moved it under the monitor and said "don't worry, it's technical - use the keyboard" - as the expression goes he was happy as Larry with that - showed him some keyboard shortcuts and he was on his way!