Saving Power or Wearing Out Your Kit?

I recently had a letter published in my favourite computing magazine, PC Pro. The topic I addressed was that of whether powering PC equipment on and off does it any harm or not. I wrote thus:

"I have been following your campaign to get us to switch off our computer equipment with interest these last few months. I absolutely go along with you on this, and I have been encouraged to switch off even more of my equipment at night as a result. However, I must say that I'd draw the line at my PC powering off relatively frequently during the day, not for any time wasting or ecological reasons, just simply because surely this must wear it out more quickly? I've noticed a couple of brief mentions in the magazine that PCs and monitors these days are happier switching on and off than they were, is this demonstrably true or does it just suit your argument?

It has frequently been my experience that it's at the point of powering up computer equipment when things go wrong. I'm no scientist, but surely the change from hot to cold to hot etc must put a strain on electronic equipment? Do modern TFT monitors mind going on and off frequently? Do PC processors suffer wear from the huge temperature changes as they power up and down?

I would be a total convert to the whole switch-it-off debate if you could persuade me there was no damage being done. Any chance of such a test appearing in the magazine?"

They were very nice to publish the letter (well, an extract from it, actually), however I was somewhat dismissed as being someone who was harking back to the days of mechanical devices, and everything was okay now.

The following month, a like-minded soul had his letter published as a follow-up to mine, again questioning this assumption that things are okay these days.

I just don't think they are, and I again emailed them, thus:
"You mentioned my worry being a hangover from the mechanical world... well let me give you another similar analogy. With aircraft, though total flying hours is used to determine if a plane is worn out, what they really worry about is the number of landings. That big thump does more damage than cruising along for hours. Is it maybe not the same with switching electronic gear on and off?
 
Now then... "News" in issue 151... "But it does save £50 per year on power" when referring to Vista's default power settings... it won't save anyone 50 quid if in fact it shortens the life of the equipment... in fact it will cost a packet in terms of hours lost and hardware replacement. I would really like to see an electronics brainiac's response to this... like your article on what kills hard disks... surely the manufacturers do research of this nature... someone must know for each component what the actual damage (or not) of powering on and off does to each component?"

It would be good to get a definitive answer on this, as a recent tv programme highlighted just what a large carbon footprint making a PC causes. If we end up breaking them by attempting to save a little power, that can't be right can it?