I have some questions about this subject.  I like to leave my
computer on if I think I'm going to be using it withing the next 2 or
3 hours, but I get sick of my Dad constantly coming up to me and
asking "Why is the computer on if you're not using it?"  I also
wonder about my computer being harmed by fluctuations in voltage from
other things (garbage disposal, etc.)  Here are my questions:
 
How much harm do voltage fluctuations cause?  My computer does not
share a circuit with anything big but our my light dims when a
refrigerator comes on or the garbage disposal is turned on (whose
doesn't?), and also when the washing machine does anything.  All
these things cause a drop in voltage which is harmful to a computer,
right?  I also notice the fan in my System Saver turning at different
speeds.  Is it safer to turn it off and back on when I want to use it
or to leave it on?
 
How much electricity does my computer use?  I have an Apple IIgs (ne
flames), with a Kensington System saver GS (1 electric fan inside),
an AppleColor RGB monitor, and an EXTERNAL 3.5" HD (1 fan and its own
P/S).  How do I translate this into Kilowatt-Hours?  Also, how much
of this is used by the monitor?
 
Does the monitor use considerably less juice when the screen is
totally black but still on?
 
Many computers spin the HD up and down constantly to save power.  I
always thought this was harmful to the HD and defeats the purpose of
leaving the computer on in the first place (except portables).  Is
this true?
 
Thanks for the Info.  I think this will help lots of people.