I deal a _lot_ with new users, so my answers are a bit different. I use
precise, non-standard (but descriptive) terminology. My goal is to employ
labels such that non-users can understand instantly what I mean.
  For computers like the C-64, the TI-99/4a, Atari 800,
etc. I call the CPU
 a "console". 
I call 'em a "keyboard", as that is what they look like.
  The all-in-one dealies like the TRS-80 Model II/III
and their ilk would
 be "computers" 
Me too. More precisely, "old-style computer"
 Piece-part systems like the IBM, I'd call "systems" because you have a
 system consisting of a CPU and peripherals, such as the keyboard, 
monitor,
  disk drives, perhaps a mouse... 
I call the --
Monitor => Screen
Case => System box
I always stress that the 3 1/2" is called a "floppy ", because a surprising
number of people think that they are "hard drives". I also see them
commonly called "tapes" (and installing a program is commonly called
"programming")
 Also, things like a PDP or DG Nova would be "systems", but I think people
 prefer to refer to them as "mini's". 
I just call them computers -- newbies generally don't know the difference.
(Besides, if you gave up your old stuff and all got PC's with Win95, you
would have _real_ computers and get _real_ work done....snicker snicker.)
(Quick! Now, I gotta change my e-mail address, lest I be buried under tons
of irate e-mail...)
manney(a)nwohio.com