Desirability factors:

Reliability
No matter how fast your computer is, if it’s broken, your computer speed and your productivity are zero.

Features
Some features are standard, some are extra. Not all features are created equal. Getting the ones you need can require some careful shopping. 

Expandability
Although your computer may have today’s latest features, next year many new features will be available, and you don’t want to buy a new computer to get them.

Comfort and convenience
Operating your computer should not be painful. That discourages use, and therefore, productivity.
 

Speed

CPU speed
The speed of the chip inside your computer, called the CPU (Central Processor Unit), is a big factor. Thanks to the competition between AMD and Intel, we now have CPU chips that operate at speeds up to 1 GHz, or 1,000 MHZ. While many of us may not need a computer that fast, lots of folks do. If you create or edit large graphics files, including video files, play advanced games, or work with other large files, you’ll appreciate the fastest processor you can afford. Similarly, if you do a lot of multitasking, a faster processor will help. However, the real benefit of the 1 GHz chip may be that it drives the prices of slower chips down so they are more affordable in typical systems. Thus we currently have a market where the slowest computer you can buy off the shelf has a CPU speed of at least 500 MHZ, which by any reckoning is really fast. Laptops may be a little slower — but only a little.

Regardless of which chip your computer may use, 500 MHZ is fast, but there are some differences between the different chips. I will attempt to make some generalizations, but caution you that they may not always apply. For a chip running at a given clock speed, AMD’s K6-2 chip will usually be the slowest. Somewhat faster is Intel’s Celeron chip (currently available in 700, 667, 633, 600, 566, 533, and 500 MHZ versions), followed by AMD’s Athlon. The fastest chip will be Intel’s Pentium III, currently available in 1.0GHz (1000MHz), 933, 866, 850, 800, 750, 733, 700, 667, 650, 600, 550, 533, 500 and 450 MHZ versions (the 450 MHZ version is for laptops). AMD has released two new chips. The Duron, which should be priced near the Celeron level, and offer equal or better performance. Initially, Duron chips (made in Austin) will run at 600 MHZ, 650 MHZ, and 700 MHZ. AMD has recently released a new version of the Athlon (featuring performance-enhancing on-chip L2 cache memory), which is fully competitive with the Pentium III, and probably cheaper. Computers with the new Athlon chips are designated as having performance enhanced cache memory or perhaps some other term. If a computer with an Athlon chip is not labeled as having the new chip, assume it has an old one. The new Athlon chips are available in clock speeds of 1GHz, and 950, 900, 850, 800 and 750MHz. 

Savvy buyers know that often the chip with a speed rating one or two steps down from the fastest model is the best value, selling for hundreds of dollars less than the fastest. For example, the Dell Dimension computer with the 1 GHz Pentium III currently sells for $770 more than their computer with “only” an 866 MHZ processor.

Memory
For Windows 98, Second Edition, or Windows Millennium Edition, 32 MB is the minimum you should consider. 64 MB is better, and 128 MB will help with processor-intensive tasks like video editing, complex graphics, and games. For Windows 2000, 64 MB is minimum, with more memory resulting in faster operation. With memory at or near its all-time low price, there’s no real reason to have less than 64 MB.

Hard drive speed
IDE drives come in two speeds: 5400 RPM and 7200 RPM. The latter drives are distinctly faster. ATA 66 IDE connections are faster than other types. ATA 100 connections may be even faster, although somewhat rare at this time. An Ultra DMA connection is not the same as an ATA 66 or 100 connection.

Video card speed
A computer command is not completed until the results are displayed on the screen. So the speed of your video card, which constructs the images that are displayed on your screen, is an important factor in the perceived speed of your computer. Advanced game graphics in particular demand all the speed your video system can deliver, and are responsible for the rapid development of graphics cards with three-dimensional capabilities. These cards download many of the graphics computational tasks to the video card, freeing up the CPU to run programs. That’s why they are sometimes called graphics accelerators. 

If you’re not a gamer, and run mainly so-called business applications, which use mostly two-dimensional graphics, you won’t get a lot of benefit from the latest 3-D video cards. Not that they don’t handle 2-D graphics very well, but most of their advanced graphics concentrate on their ability to display 3-D images rapidly and realistically. But don’t invest a lot in a video card if you aren’t going to need its capabilities. Many home computers skimp on video cards to save money, by using graphics circuits built into the motherboard and sharing memory from your computer’s main RAM. That’s guaranteed to be slow. 
 

Reliability

1. users have much greater interaction with computers, and have more opportunity to screw things up. Not many computers have remote controls,
2. computers are built out of major subsystems (the drives, video cards, modems, etc.) that are designed somewhat in isolation, so incompatibilities can easily occur; or
3. due to competition to get a product to market, the software drivers that make the individual pieces work with the operating system are not fully developed.

Note that PC Magazine’s survey shows an entry for locally built computers — the ones built by shops like many of the advertisers in PC Alamode. That rating is an average nation-wide, but indicates locally-built computers are pretty good, and I’m guessing that their local service is what the survey respondents really liked.
 

Features

Expandability

Motherboard slots
Your motherboard is the big circuit board inside your computer that connects everything together, and provides slots into which to plug expansion cards. Some computers come with all or most motherboard slots filled, which prevents your using them for expansion. Using external devices can circumvent a motherboard slot shortage, also.

Power supply
Your computer’s power supply must be able to carry the load of all the devices that you install inside the case. Some power supplies offer less than 100 watts of power, which is marginal. Look 
for a power supply of at least 200 watts.
 

Comfort and convenience

Accessibility of ports
If you have a digital camera, a personal digital assistant (like a Palm Pilot or Pocket PC device), or a digital video camera, you will want to connect it to your computer sooner or later (sooner for the PDA). Front-panel USB and IEEE 1394 (FireWire) jacks like the ones on some Compaq computers make connecting your external devices easy. 

Monitor size
Larger monitors show more information on-screen, enhancing Windows’ performance. Or you can set the monitor to display larger objects, making it easier to read. Get a 17-inch monitor unless your budget is extremely tight. Also, a lousy picture can rapidly cause eyestrain, so be sure your monitor displays bright, sharp images with no distortion at the edges of the screen. I don’t know of any way to ascertain this except to look at the screen yourself. Or you can read reviews of monitors in computer magazines like PC Magazine, which frequently rounds up a large collection of monitors and subjects them to benchmark measurements to evaluate their performance.
 

Additional buying tips

Understand the warranty. If your vendor requires you to carry the computer back to the shop, find out if you have to remove any devices you installed yourself, like a tape backup drive or extra memory.

Beware the “package” system, which includes a monitor, printer, and possibly other items like a scanner or video camera. In most cases, these systems skimp on one or more components (often the printer) to keep the price down. There is no reason not to pick your own printer, and for that matter, your own monitor. Any monitor will work with a given brand of computer; you don’t need one from the same manufacturer that made the computer.

Deal with reputable vendors. This should be obvious, but I often hear of folks buying at a swap meet from an out-of-town vendor, or on an auction site like eBay. The latter can produce dramatically low prices, but you’re on your own if the actual merchandise doesn’t meet expectations. As an eBay aficionado, I have found most sellers to be honest and eager to make things right if you’re not satisfied, but there are a few bad apples.

Don’t be afraid of direct-to-customer sales from the big companies like Dell, Gateway, and Micron. Or even from Compaq and IBM. They have a reputation for helping users that is far superior to the help you’d expect from a big computer/appliance store. Many are open 24 hours a day, and offer on-site service in your home for part of the warranty period. Review the reliability ratings in the table before placing an order. Also find out about return policies; do you get a 30-day no-questions-asked return privilege? Or is there a restocking fee?

Consider the online outlet stores run by the big direct-to-customer companies. These may produce greater savings by selling returned or repaired computers, which have the same warranties as new units.

Shop, shop, shop! Like any other commodity, knowing what constitutes a good value in a PC  is essential to getting a good deal. 
 

In closing