» Footnote on power protection «
A final word
Pedantics please bear in mind I'm a computer consultant, not an electrical engineer, and that this is aimed at the lay person. I wrote this after visiting and reading literally hundreds of web pages and white papers on the technology and trying to condense it all as much as possible. I will probably make a few more revisions until I'm happy with it.
If there are still technical errors or omissions it is due to the level of misinformation and obfuscation on the subject, largely caused by suppliers with a vested interest in spreading FUD.
The fact the power and utility companies aren't exactly forthcoming about the quality of their own output doesn't help. As well as obvious internal monitoring, there's even power quality database management and analysis software such as PQView which can output graphs to the web. True, most of it will be utterly meaningless to nearly all of us, but there's absolutely no reason - besides cover ups - that power companies can't prominently display a link to a page giving simple statistics and graphs of line quality by day, week, month and year.
Of course, insurance companies would love it. The first time you tried to claim on a fried computer they'd point to the graphs and renege of the payout because you should have been aware of on-going line conditions and installed a UPS. 
It's getting to something when I can easily find the contact details, even the home address and phone number of a power station's manager, yet I can't find anything, anything at all, about their outages. I mean, look at International Power, they have no problem displaying their share prices on the US and UK stock exchanges on their home page…
Think about this (made up) list:
HonestPower PLC, Line quality for March 2005
Corrections and events causing…
- possible spikes: 189
- possible sags: 1,389
- possible brownouts: 389
- blackouts:(under 1 ms): 23
- blackouts: (under 1 minute): 0
- blackouts (over 1 minute): 0
- …
Only government intervention will persuade them to do that, because they simply don't want to be seen less than perfect. True, this will make no difference or account for all the events that effect the power lines after they leave the plant, but seeing in black and white 'n' events a week that could potentially harm your nice new plasma screen, your computer…
In the same way cigarettes have tar levels stating 'smoking can damage your health', you need to be aware that 'mains electricity can damage your computers'. The worse the quality of your power, the more likely you are to experience a terminal error.
BUT, and it's a big but, AT LEAST 60% of the problems are believed to caused by the other equipment YOU are running, and how you have them configured. For instance, running your cable lines parallel to pipes and, especially power cables (in the walls) can play havoc. USB cables cause a host of potential problems that Ethernet ignore, and so forth.
So, don't shoot the (power) delivery messenger just yet, eh! 
Anyway, if you want to correct me, and/or point me to other - reliable - resources please do.
