It attacks computers via distribution - often unknowingly - through email attachments, software downloads, and even some types of advanced web scripting. Viruses that destroy data are known as Trojan horses, viruses that explode their attacks are called bombs, and viruses that duplicate themselves are called worms. Be aware however, that because shareware is not commercial software, you may not experience a full program the way you would if you bought the software out of a box. Shareware may or may not be limited - meaning that some functions may not be available to you until the program is paid for. These limitations are often small and don't interfere with the way its full version operations. Regardless of the device, the operating system installed onto it serves the same purpose across the board: to enable user-to-hardware communication. When you think about upgrading your computer to a new operating system, be careful to make sure that you have the necessary hardware components. We tried to upgrade one of our Windows 98 machines to Windows XP, but we were cautioned that the former may not be hardware compatible with XP technology. But when one command conflicts with another command - or when one command asks for a process or information that isn't available, the computer returns results that aren't useable. That's an error. A prime example of this kind of error is when users attempt to use software that isn't applicable for their system. Today's users require full multimedia capabilities, a wide range of graphics tools, and accommodations for the various portables we now enjoy. These extras aren't included with "what comes out of the box," and the only way to get them is to accessorize. To illustrate the importance of accessorizing, we like to use the "plain dough" analogy. Surprisingly, you may even get a helping hand from the salespersons at your local computer store. We don't recommend that you make this your first pit stop when you experience a problem, but we don't recommend that you rule this option out altogether either. Computer salespersons are hired for a reason - and that's their knowledge.