"Hello, I'm having a problem with my Linux computer. The XXXX application says it won't work because it has the wrong version of something called ffmpeg"
"I see. Ok, I'll talk you through updating that package. Do you usually use yum, yast, apt-get, or portage?"
"What are those?"
"They are package updaters. Ok, do you use Debian, Ubuntu, Suse, Gentoo, Fedora, or Linspire?"
"What are those?"
"Ok, maybe it would be easier if you just brought up a terminal window and I'll tell you letter by letter what to type"
"Ok, how do I bring up a terminal window?"
"Well, if there's not an icon on your desktop, then it depends. Does your Linux computer use Gnome, KDE, XFCE, or Enlightenment?"
"Um, what are those?"
"Those are different windowing environments you might have. Depending on which you have, the menus and interface could be very different."

(pregnant pause).

"I see ... would it be possible to install Windows on this machine?"
"Bring it in and we can do it overnight."
"Thanks."