Buying a computer can be an overwhelming process. There are so many components to consider that it can be difficult to know what to get, let alone how much you should pay. Even if you have bought a computer fairly recently, the rapid pace of change in this industry means that older guidelines may not hold much weight anymore.

This buying guide is designed to give you the facts you need to purchase a desktop computer for the office. You can choose to read this guide from beginning to end, or jump directly to a section of interest by clicking on the links above.

The first decision when choosing a computer is whether to purchase an IBM-compatible PC or a Macintosh system.

PCs currently dominate the business computer market, particularly in large firms and financially oriented departments. Most PCs come pre-installed with a popular operating system (OS) made by Microsoft Corp. known as Windows. The most current version of Windows designed for the business environment is called Windows 2000, but many computer manufacturers are still selling systems with Windows 98 or Windows NT, both of which are still perfectly adequate operating systems for your small business needs. And if you later decide that you need Windows 2000, an upgrade can be purchased at significantly reduced price.

Macintosh models have less than 10% of the overall market, but are very strong in the educational, graphics, and multimedia segments. Because of its smaller market share, some software is not available for Macs. As for its operating system, Macs use a homegrown windows-style OS called simply Mac OS. The current version sold in Macs is OS 9, but expect a newer version, OS X, sometime this year. If you purchase a Mac with OS 9, you'll be able to purchase an upgrade to OS X when it becomes available at a significantly reduced price.

Overall, the best choice for you depends on the work you will be doing. If businesses that are similar to yours use Macs or PCs, you are probably best off making the same choice.

Once you make the Mac vs. PC decision, the next task is finding the right brand and model.

Currently there are many brands of PCs on the market, ranging from well-known companies like Compaq and Dell to no-name brands assembled in basement apartments. The Mac market is far simpler, since only Apple now sells computers using the Mac operating system.

When deciding among brands, it is important to understand that desktop computers are simply a combination of very standard parts. By mixing together processors, disk drives, and other hardware in various combinations, manufacturers can create a system to meet almost any need. The primary difference is in the components that are used.

As a result, the next step when choosing a computer is to get a handle on what type of components will be best for you. By getting the processor, memory, hard drive, and video support you need, you can be sure that the computer will be up to the task.

A computer's processor is the "brain" of the machine, controlling what the computer thinks and does. The processor is also often referred to as the central processing unit (CPU).

The performance of a processor is generally measured by its internal speed. The unit of measurement typically used is megahertz (one million cycles per second). So, theoretically, an 800 MHz computer processes data internally (calculates, compares, etc.) twice as fast as a 400 MHz computer. Things like disk speed and memory, however, also play a role in the computer's overall performance.

PC Processors

Most high-end business PC computers use the Pentium III processor, which comes in speeds ranging from 450 to 933 MHz (a 1.13 gigaherz version is expected Q2 '01).

Intel also has a very new processor that was launched on November 20, 2000, called the Pentium 4. It's currently available at clock speeds of 1.4 and 1.5 GHz. This processor is aimed at the extremely high-end portion of the computer market, particularly for workstations, but should eventually work its way into the mainstream.

You may also see some other variants of the Pentium available for sale. PCs based on the Pentium II are typically two or more years old, but will be fine for general office applications. There are also the Pentium Xeon and the Pentium Titanium, which are designed for servers rather than desktop PCs.

Most budget PCs - PC's priced less than $1000 - use Intel's Celeron processor. This chip ranges in speed from 500 to 733 MHz . Celeron chips are designed with less performance level than the Pentium chips so the computers that contain them are aimed more at the home and college dorm environment rather than the business environment. But a computer with a Celeron chip would also be perfectly suitable for any employee who only uses a computer for light office tasks such as scheduling and data entry.

Businesses can also choose from a number of non-Intel processors. Competing against Intel's fastest Pentium III is AMD Corp.'s Athlon processor. It is available in speeds that range from 850 MHz to 1.2 gigaherz (GHz), and has performed very well in tests against the Pentium III. AMD also has a processor called Duron - available in speeds of 800, 750, 700 MHz - that competes with the Pentium III of equivalent speeds.

AMD also makes a process called the K6-2, which is roughly equivalent to a Pentium III running at the same clock speed.

Another alternative is VIA Cyrix M2 processor and VIA Cyrix III processor from Via Technologies Inc., which compare quite favorably to the Celeron at similar clock speeds.

Mac Processors

For buyers interested in Apple computers, they use chips that are exclusively available to its Macintosh computers. The Power Mac G4, ideal for any business user, comes with a processor known as the G4. Though it's only available at speeds of 400 and 500 MHz, the G4 has performed extremely well in tests against Intel's Pentium III chip.

The Power Mac G4 is also available with a dual processor configuration - meaning you get two G4 500 MHz chips in your computer for double the performance.

Macintosh also has a line of computers called iMac, which are generally targeted toward the average consumer. But because of their extremely attractive appearance, combined with robust performance, many small business users have purchased iMacs for use in high-profile situations - like a receptionist's desk in a front lobby. The iMac, as well as all of Apple's notebook computers, uses an older version of its processor called the G3, which is currently available at speeds that range from 366 to 500 MHz.

Memory, also called RAM, can be best thought of as the workspace for the processor. A computer with lots of memory has plenty of room to run multiple applications. In contrast, a system equipped with less memory requires the processor to waste time shuffling data around to make room for the next bit of work. If memory space is very limited, the processor may even need to temporarily store data on the hard drive, a process that significantly slows the entire system.

As a result, the amount of memory in the computer can have a dramatic effect on how fast the processor operates. Most new computers are equipped with at least 64 megabytes (MB) of memory. This is enough to load most operating systems and run most programs.

Adding memory to a computer typically costs less than $3 per MB, and memory can easily be bought and installed after the purchase.

Most computers come equipped with a hard drive to store applications and documents. Hard drives have dramatically dropped in price over the last few years, to the point where few systems are even offered with anything less than a 10 gigabyte (GB) drive. High-end systems commonly offer storage capacities as large as 30 GB.

If this sounds like a lot of storage, consider that applications now routinely take as much as 10 to 25 MB apiece. An operating system such as Windows 98 will occupy as much as 200 MB - or even more. Complex files such as sound, graphics, or video can swallow up to 100 MB of storage space.

On Windows-based PCs, video performance plays a critical role in how fast the computer appears to operate. Even with a Pentium III processor, you may find yourself twiddling your thumbs if the system takes a long time to redraw images on the screen.

The key to video performance is the video card. The card determines the number of colors the monitor will display, as well as the resolution and the speed at which the images appear.

Most systems today come with cards that can handle eight-bit color, or 256 colors simultaneously on a screen. For users requiring more realistic images, many systems can be equipped with video cards offering 16-bit or 24-bit color. These can display 65,000 and 16.7 million colors, respectively.

To handle the enormous amount of data that comes with displaying so many colors, good video cards include specially-designed processors and memory (video RAM). Cards typically come equipped with 1 to 4 MB of video RAM. If you expect to use a large monitor or need to display many colors, however, look for a card with 4, 8 or even 16 MB of video RAM.

Computers are sold through a variety of channels, including retail stores, direct vendors, mail order firms, computer stores, and value added resellers (VARs).

Retail stores tend to have fairly good pricing, but offer a limited choice of models and almost no advice. They are usually a good choice only if they stock exactly what you need.

Direct sales vendors such as Dell and Gateway 2000 are significant players in the computer market. These firms sell direct from the factory, and tend to combine good prices and attractive service policies.

Mail order stores are most suitable for very knowledgeable consumers. Mail order offers the best bargains, but also the greatest risk of receiving a sub-par system. As a result, businesses buying through mail order should be careful to investigate both the firm and the model before buying.

Computer stores are often a good source for advice and technical help. Most computer dealers stock a wide number of models, plus most important peripherals. However, dealers tend to be more expensive than other sources.

VARs generally have the highest level of knowledge about systems, particularly in setting up computer networks. While you can expect to pay a 10% premium for the service and advice of a VAR, you will receive on-site assistance to help set up the system and fix any problems that may arise.

If you haven't purchased a computer in a while, current pricing may pleasantly surprise you. While the typical business computer once cost $3,000, businesses today can buy a capable model for around $1,500. For companies on a tight budget, consumer-oriented PCs have dropped to well under $1,000. Although you may find the features or support policies unacceptable for the workplace, a low-end model may be fine for relatively limited applications.

The processor is the single most expensive component in a computer. As a result, the age and the market supply of a processor have a major effect on pricing. In the first few months after a new processor is introduced, production lines are usually not fully up and running at top speed. This is a bad time to buy, since prices are very high and there may be unresolved compatibility problems with some systems.

Once a processor is superseded by a faster version, its price tends to drop dramatically. This is usually the best time to buy. Although further price cuts are inevitable, waiting any longer risks shortening the useful life of the computer. Purchasing just after the introduction of a new chip gives you the best combination of price and leading edge technology.

No matter where you buy, keep in mind that this is an extremely competitive industry. Any vendor will be willing to negotiate with you, especially if you can be flexible in terms of configurations or accessories - or if you are buying in bulk.

When comparing prices, make sure to keep in mind the cost of software. Manufacturers can bundle software such as Microsoft Office for far less than you will be able to purchase it on your own. As a result, it may make sense to buy a more expensive computer if it offers the software you need. On the other hand, do not be seduced by software bundles simply because they provide a large number of applications. A program you will not use is worth absolutely nothing.