I prefer to divide computer users into three categories. 
Yes, there are sub-categories and some users overlap or fall between two types of users.

After years of experience in working professionally with computer users--and helping friends, I've found that this hierarchy holds up well.

I'll start with the user who views the computer as an appliance. Yes, their machine may as well be a toaster or an iron.
As with all three groups, this person may use a computer at home, at work or both.  This group is distinguished (snobbery is to be avoided) because for them the computer is an aid and not much more. 
In fact, many workers are not sure if a computer truly is an aid in all circumstances. There reason is: "Sure I am able to get more work done---that simply means my employer is loading me up with more work." And many are probably correct. Oh, sure, word processing has made their life easier. One can delete a word or a phrase instead of starting out with a new sheet in the typewriter.  Countless other types of software has made life easier for workers. Since we don't have Secretaries any longer --- the title is Administrative Assistant, so too have the duties changed. Yes, a computer means that any assistant is probably going to be performing more complicated tasks than the same person in the same position twenty years ago.
But this group is limited in their appreciation of the computer.  When something "new" is available they may be reluctant to adopt it.  They rarely think of how their use of the computer can be enhanced, they simply are satisfied with whatever state they are in.
At home, they probably limit their use to the Internet, perhaps they are doing their bookkeeping on a computer.  The greatest percentage of their time is devoted to using the computer for e-mail and an occasional search. They may shop online but they were probably timid to begin and started late. While appreciative of the advantages brought to them by technology, they could probably go back in time and only rarely complain about their loss of the the computer.

The second group of computer users view the computer as a true utility. They were probably first exposed to a computer at a younger age than the group above, but there are many in the above group who have been operating computers for as long as this group. Age of exposure is not crucial; group two only "tends" to have had the opportunity at a younger age. As with any behavior, the earlier one is introduced to, or learns something, the more likely they are to embrace it. But many in this group were exposed to a computer well after their formal education ended.
No, that which separates this group from the above group is this group is more aggressive in pursuing the possibilities the computer holds. While the first group dreads the thought of new hardware or software, this group not only sees it as a challenge but operates under the assumption that "newer/faster" is truly better. Group one will probably recoil or at least be apprehensive to change. Group one probably doesn't know much at all about the configuration of their machine.  They make know the manufacturer and that's about it. Group two is aware of not only what they have, they know what they are missing if they are not up to date.  Group one only takes the "next step" step when they are forced to. Group one probably never changes the settings on their computer or customizes the software or the programs they use. Not only will group two maximize both of these areas but they explore "how" whatever computer related task they are dealing with can be improved by getting even more out of the tools they are currently using. While thy are pro-active, there is still a line which they will not cross.   That is, even though they are comfortable with manipulating most of the setting available to them (both with software and hardware) they rarely venture outside the bounds of the particular hardware/software available settings.  If it is is in the manual, fine---they probably rarely implement "undocumented" procedures.

Group three is often referred to as a "power user". I don't have a problem with that term so long as it's qualified.  That is, a power user is often used to describe "quantity" of use.  How much, how often an/or how complicated their tasks.  If measured in hours per day or sophistication of software, many would qualify as a power user though they aren't.  Many people who spend all of their time at work with a computer wouldn't even qualify as group two.

A power user need not even use a computer at work, though that probably would be an exception.  So, the power user (yes, I'll use the term) is defined by "how" they perceive the computer. Yes, group two is fluent, aggressive and probably technically able to be a power user.  For the power use it is a choice (many times a risk) to milk each ounce of efficiency and productivity from their machine. 
A power user will adjust anything and everything possible to adjust---whether it's software or hardware.  The power user views a new computer or an application as an opportunity to make improvements upon its default settings.  Before they begin to use anything new they set about to customize it. Using the same out of the box setup, group one may not recognize what the power user has.  Group two will understand it, perhaps appreciate it but would likely not be driven to "personalize" every available setting. Again, group two would be willing to "copy" the settings or configuration of someone if that person assisted them. But they probably would hesitate to apply non-standard methods based on hearsay alone.   
Sadly, the power user is misunderstood.  They are often described in derogatory terms and there is the inference that they "don't have anything better to do". Group one believes the power user is more of a hobbyist (who would devote any extra time if "their computer" is already fully functional. Group two may be even harsher.  Since they are already thinking outside the box, they probably don't (are aren't willing) to believe the manufacturer has limited their potential.  Group two has already done everything possible (or at least that which is available in the manual) -- anything beyond may involve risks and if "something went wrong?", well, who would they turn to?
However, much of what the power user accomplishes would improve the quality of life for even the most computer phobic user.  No, group one will never (couldn't) take it upon themselves to apply the techniques of the power user, but they would benefit if a power user analyzed how group one uses their machine and applied or manipulated the basic setup which group one is using.
Group two has power user potential.  After all, they would welcome any improvement (and they may own or use more sophisticated equipment than the power user).   Yes, a power user can own a five or ten year old machine and get more out of it than someone from group two would achieve with a brand new system.

Yes, I am probably a power user.  I have dug deep into processes, not necessarily to see how or why they function but to enable myself to adjust, (tweak) every ounce of utility from them. I'm selfish an cheap!  It isn't a hobby and certainly not a necessary function of my job.  I've become a power user because it is worth the small effort to improve upon what is delivered to me.  I am able to perform a given task faster, better and safer because I have decided to venture into areas where a small minority of users share their stories.  Taken to the extreme, one could isolate one particular sub-group of power users who form loose alliances and develop applications and make them available for free.  I will detail the advantages of "open-source" software and argue why it has the potential to offer the greatest change since personal computing began over twenty years ago.
I will provide in the following pages advice, tips and plain old fixes that will allow everyone (including some power users) the opportunity to improve the quality of their computing.

At worst you will find solutions, increased productivity and a greater level of comfort in your current tasks.  At best, you can learn some basics which are necessary for your security, that could help prevent a disaster or if you are faced with a problem you won't be helpless.

This section will be divided into four categories:

1. Prevention
2. Maintenance
3. Recovery
4. Increased productivity

Before I begin I'd like to introduce you to something so fundamental it precedes any advice or direction I could offer. I will provide you with the means to access more information faster and with greater ease that you thought possible.  Less than ten percent of the population makes use of this resource so I am comfortable in asking you to take this first step.  If you never intend to leave group one but have access to the Internet, you will benefit. In fact, you will join a small minority of users that don't necessesarly have any more interest, aptitude or ability than you.  And if you are a power user? Well, there is a good chance you haven't been where I'm going to take you first.

So, strap on a beanie with a propeller and let's go for a ride!