I'm confident in my ability to change a light bulb. But cutting drywall to move and rewire a junction box is a task I probably wouldn't take on myself. I'd call an electrician for help because the risk of damage to property or me is too high.
I can change a flat tire on my car. But changing the timing belt is a task I wouldn't even attempt. I have neither the tools, nor the skill to do it.
From time to time I get calls from distressed clients after they have taken on computer task that was beyond their scope of knowledge. Most often the call for help is to revive a dead PC after its owner went on a reckless file-purging rampage to "speed up" the computer. All it takes is one careless or inexperienced file deletion to render a PC unbootable.
A myth I've had to bust for more than one person this week is that a large number of files stored on a computer's desktop slows it down. This isn't true. Computer speed is a function of processor power, amount of memory, hard drive access speed, the resource-greediness of the software installed and how many software programs your computer is trying to run at once. Except in the case of a viral infection, a computer becomes "slow" as a greater number of newer, more-demanding software programs tie up its resources -constantly.
Another contributing factor is what I call the PC's inner sanctum -officially called system registry. It is a database that stores information about software and hardware components. Over time, the registry's information can become inaccurate and programs that don't uninstall correctly can leave fragments of information that can also affect computer performance. Tampering with the registry, like deleting the wrong files, can convert your PC to a paperweight. I don't recommend registry editing unless you really understand it.
Fortunately, some excellent software is available to safely help you clean your computer's unnecessary files, its registry and more -without having to hire an IT expert or get a computer science degree. Beware, however, because there are hundreds of titles that pose as "good" utilities, claiming to help clean your computer and registry when in reality they infect it with malware that slows it down more.
A legitimate utility and one of my favorites is CCleaner (.com), a utility that comes preloaded with all the expertise you need to give your computer a safe once-over. CCleaner is quick, small, thorough and free. It will safely clean up erroneous entries in the registry and remove your PC's temp files. It will even wipe your browser activities to protect your privacy too -if you wish. If it helps you, consider sending the authors a donation -they'll appreciate it and continue to write cool software.
After having tried to manually tweak many a computer to maximize performance, it is great to find such a useful, free tool that makes quick work of a task that would normally require hiring an expert.