There is a common misconception about monitors. It goes something like this: as monitors are the only main component of a PC system that does not affect performance speed, then you will not lose out by opting for the cheapest model available.

Admittedly the loss of productivity caused by eye strain from using a too small or unclear display, more than negates the benefits of a small percentage processing boost got from the latest RAM or processor.

Tube type

While the supported resolutions are an important factor in determining which monitor to opt for, there are other things to check for as well. One of the major choices will be on the tube type, and although there are a number of variations, this basically boils down to whether to opt for one with a traditional shadow mask design (for example, FST tubes) or one with an aperture grille approach (for example, Trinitron).

There are no hard and fast rules as to which is better, and you will have to look at the individual reviews to see how well the technologies are implemented, but the aperture grilles tend to produce sharper images overall.

Video bandwidth

The video bandwidth of a monitor is also important, and the figure quoted in megahertz (Mhz) determines how well the analogue signal coming from the graphics card is displayed as dots on the screen. The brightness of the dot and how long it is displayed on the screen is determined by the amplitude and wavelength of this analogue signal, and if the bandwidth is too low, the signal becomes distorted, resulting in ghosting and loss of brightness on thin lines.

Image controls

The number and range of image control options are important if you want to get the best from your monitor, and while it is possible to check the latter from the spec sheet, the only real way to find out how easy a monitor is to control, is to try for yourself.

On-screen displays (OSD) are now commonplace. A good monitor should also meet, and even surpass, a number of internationally recognised environmental standards. For power efficiency, look for Energy Star and preferably CESA DPMS support.

LCD and CRT

Recently there have been a number of cheaper flat-screen monitors appearing onto the market. But although still priced out of the reach of most PC users' purses, thin, flatpanel liquid crystal displays (LCD) are making inroads towards the mainstream in businesses where space is at a premium.

For example, even 14.5in LCD panels display 1024x768 pixels well, while 15in CRT monitors generally aren't usable above 800x600 pixels.

The standard sales proposition is that LCDs save you space and therefore money. The oft-quoted example is the trading-room scenario: traders typically use a pair of 21in CRTs.

By the same token, LCDs aren't affected by EMF: some electrical environments are hostile to CRTs.

Displays typically have a usable life that's perhaps twice that of the PC's system unit. LCD displays are very reliable, offer low support costs and enjoy an element of future-proofing.

Disadvantages of LCD

But there are downsides to LCD. Conventional CRT units continue to offer the best value for money, at a quarter or third the price of comparable LCD displays. A 15in LCD, for example, sells for about £725, while a 17in CRT sells for about £175.

The introduction of flatter tubes and short-neck tubes means there's still plenty of life in CRT, and price erosion continues apace - something that's ground to a halt with LCDs.

Colour calibration is another area of weakness: graphics professionals who demand the ultimate in colour fidelity are able to precisely control factors such as colour temperature on a CRT, something that is much more difficult with an LCD.

TFT technology

On the technology front, TFT technology continues to evolve, and manufacturers continue to develop displays that have higher resolutions and deliver brighter, more contrasting images with wider viewing angles.

Manufacturers are also looking to further shrink the casing size with thinner bezels, while at the same time increasing LCD panel sizes.