We can do more with computers today than we ever dreamed we could. With options like accessing the Internet, word processing, email, and image editing, it's hard to see how one could function in today's fast-paced world without a computer.

A desktop computer usually sits on top of a desk, although you always have the option of placing it anywhere. The basic components are the tower, keyboard and mouse. Most desktop computer towers stand vertically, are a little more than a foot in length, and are becoming smaller each year. Desktop towers usually have plenty of room for upgrading via expansion slots. A computer monitor is required but usually not included when purchasing a desktop computer. Virtually all PC desktop computers have upgradeable memory, a hard drive (used for storing software and files), many have CD or DVD players (some even have CD recorders), a modem (for telecommunication and Internet access), video and sound processors and an entire array of connectivity ports. All new models are shipped with a manufacturer’s bundle of software (often pre-installed on the hard-drive), with a current version of Microsoft Windows.

Every computer has a central processor, which essentially functions as the "brain" of any computer. The central processor manages and processes all the steps that are required by the program application. There are two current competing processors on the market: Intel and AMD. For most home and small office applications, there is virtually no difference in PC processors. Intel Celeron and Pentium processors have a slight edge only if you choose to network certain computers using Windows NT. All current AMD and Intel processors claim to be fully compatible with Microsoft Windows 2000.

The big issue with processors is how fast they operate. The speed of currently produced central processors for desktop computers ranges from 300MHz (MHz = Million cycles per second) to 1GHz (GHz=Billion cycles per second). Processing speed is really dependent on your needs. For accounting or word-processing, speed is not an issue. If you are interested in high-level graphics and multimedia applications, a higher speed processor is highly recommended. Also, keep in mind that the higher the processor speed, the more expensive the desktop. In many cases, after owning a PC for a while, you may also have the ability to upgrade these processors, as needed.

The Data Bus
Another factor that affects the speed at which a computer carries out operations is the bus speed. The interface in which the computers processor communicates with part of the computer is called a data bus. Bits and bytes of information are continually being transferred using these buses. Different processors transfer information at different rates. A processor with a wider data bus can move more information more quickly. You want a higher bus rate if you often work with graphics and play computer games. If you are just shopping for a good bargain, and will occasionally deal with graphics, you can settle for a lower bus rate without worrying about it effecting computer performance. Look at the chart below for the different processors and their bus rates.

The amount of RAM (Random Access Memory) that your computer needs may be associated with the size of a work area (i.e. the top of your desk). The operating system (Windows) and each program that you use requires a certain amount of memory space. If you plan on having several programs in use at one time, and if you create large files, you need more workspace for overall efficiency. Most computers come with either 64MB (MB= 1 Million characters of memory) or more. 64MB RAM is considered sufficient for most home computer uses while more RAM (about 128MB) is desired for large business needs or professional multimedia applications. Nearly all computers allow owners to upgrade RAM space.

Video memory comes as a circuit inside your desktop or notebook computer and it effects how clearly you view images on your monitor and graphics. Video memory can be part of the motherboard or it can fit into expansion slots. The more video memory you have, the sharper you may view images on your monitor. Video memory enhances the ability to view text, photographs, illustrations or even movies. For non-graphics-oriented viewing, 2MB of SDRAM (Super Dynamic Random Access Memory) or VRAM (Video Random Access Memory) should be sufficient. If you work with graphics, go for 8MB or more of SDRAM or VRAM.

Video memory and processing capabilities may be upgraded by adding new Video Processing boards to a computer's internal expansion slot. Some computers include video boards that allow you to connect a VCR, TV or Camcorder to input and output video images.

Hard Disk storage capacity is not to be confused with RAM. If we considered RAM your working space on a desk, then the desk drawers would be the hard drive, where you store programs and data files. Hard disk space is measured in bytes like RAM, but the hard drive has a much larger storage capacity. Most desktop computer hard drive capacities range from 10GB to 40GB.

Many desktop computers come with a CD-ROM drive, used to run programs and software. A CD is a Compact Disc and stores about 650MB of memory per disc. Now there are recordable and rewritable CD where you have the option of saving files (music, video or data) onto a CD, but you can only do so with a special "burner" or CD Writer drive, also known as a CD-RW drive. Some CD you can only record on once, and others may be reused, erased and recorded over numerous times. However, unlike a cassette or other magnetic storage devices, CD quality is digital, therefore leaving no room for distortion.

While many desktop computers still only have CD-ROM drives, numerous recently manufactured desktops have DVD-ROMs. A DVD is a Digital Versatile Disc and stores about 4.7GB to 17GB of memory per disc. Most DVD drives can also read CDs. There are DVD-RAM drives that can record, using special recordable DVDs.

Desktop computers may come with a CD-RW (CD-ReWritable) drive. Besides being able to read music or software CDs, CD-RW drives allows you to record data and files onto a recordable or rewritable compact disc. Record anything from music to video files on your very own computer.

A feature you'll notice written in many desktop computer descriptions is 4X CD-ROM or 6X DVD-ROM. These numbers refer to the transfer rate of data from the drives to the computer. The original transfer rate from a CD-ROM is 150KB/sec. 2X is twice that rate, 3X would be triple that rate, and so on. The normal transfer rate from a DVD-ROM is 350KB/sec. The higher the number before the X, the faster the rate of transfer.

A modem is, very simply put, a device that allows your computer to communicate through a phone line. You need a modem in your computer in order to access the Internet. Modem speeds are measured in BPS (bits per second), and most computers today come with an internal 56K modem. Some higher end models now come with a DSL modem, upgrade ability. DSL connections require a monthly service charge from your local phone company. Upgrading modem speeds is also an option, if you feel the connection is too slow. It's also good to keep in mind that even though you might have a fast modem, other factors may impinge on your on-line connection speed. If the computer you dial-in to is slower than your connection, you're only going to go as fast as the computer. Also, damaged telephone wires and bad connections and even a limited RAM cause slower-than-desired connections.

Microsoft first introduced Windows to the world in 1983. Windows was intended to be an extension of MS-DOS, a graphic interface to make DOS user-friendlier. It allowed for cooperative multitasking of Windows applications, which means you may have several windows (applications) open on your screen at the same time. All PCs today come with some form of a Windows application (either Microsoft Windows 95, 98 or 2000). Macintosh computers use a different operating system, currently the OS 9, which is not compatible with Windows. Windows allows computer users to do multi-tasking.

Unless otherwise noted, desktop computers usually do not include a monitor. (See monitors for more information).

With interface or connectivity ports, computer users have the ability to connect numerous external devices. Interface ports may be located on the front or rear of your desktop. These ports allow you to attach a monitor, printer, scanner, keyboard and mouse. There may also be ports for sound and video input and output. Most PC computers come with Parallel, Serial, USB and now even FireWire, among others. with Parallel, Serial and USB ports (among others).

The most common use for parallel ports is for connecting printers. Other peripherals like backup drives may also connect to a parallel port. The parallel port of any computer is usually located on the back panel of a desktop computer. Most desktop computers come with just one parallel port. You can hook two devices up to one parallel port using a pass through adapter. However, both devices cannot be used at the same time.

USB stands for Universal Serial Bus and is one type of interface port that you may find on your desktop computer. There may be more than one USB port on your computer, and they are used for connecting devices to your computer. A USB connection allows for faster transfer of information between your computer and any device. Adding a scanner, digital camera or other gadget becomes easier and transfer rates of data become quicker than a parallel port connection.

FireWire is one of the fastest peripheral interfaces available today, which makes it great for use with multimedia peripherals like video camcorders and other high-speed devices like the top-of-the-line hard disk drives and printers, among other devices. Its transfer rate is 400Mbps, and has 30 times more bandwidth than USB. FireWire is sometimes also termed iLink or IEEE1394. Many video and audio professionals are now turning to FireWire because of its high speed, flexible connectivity and the ability to link as many as 63 devices. Newer model PC desktop computers with come with at least one of these ports. If you plan to work with transferring video and audio from external devices to your computer, make sure your computer comes with one.

DV stands for Digital Video. Many new video camcorders now record in this digital format. This format has simplified the process of editing recorded video forever. Recorded digital video is usually stored on a special tape called MiniDV, or Hi8. Once transferred onto a PC using a high-speed FireWire port, using certain software, the digital footage can now be cut and editing, then transferred with ease.