The image on the monitor must show the true colours of how it will be printed if you are to edit the image correctly. It is a vital piece of equipment and must be calibrated correctly before any printing is attempted.
The video, or graphics card (commonly nowadays an Advanced Graphics or AGP card) driving the monitor image is also critical. If the AGP card and the monitor are matched correctly the screen will not flicker and the picture will be updated very quickly. Gone are the days when I had to wait half a minute for the picture to be redrawn after moving the scroll bar! However, this speed is achieved by having plenty of fast video RAM onboard the graphics card, which unfortunately costs a lot of money.
Monitor refresh rates should be as high as possible to reduce flicker, but this is also a function of the video-card (see also the video-card page by clicking the button above left). Another important consideration is the monitor dot-pitch, the smaller the better.
After a lot of research I chose an Iiyama 15" monitor. Recently I updated my Matrox Millennium G200 graphics card with 16Mb of video memory for an ATI Rage with 32Mb, because I could not obtain an Matrox G400. Having said that, I am really pleased with the performance of the Rage card, and it cost about half the price of the G440. Space limitations restricted my use of a larger monitor, which you should seriously consider for photo editing as you can see more of the image without the tool bars getting in the way. 17" monitors are now low enough in price to make them attractive for home user.
The Iiyama range of monitors also have adjustment of the Red and Blue guns, so you can adjust the balance to the Green gun and adjust the colour balance or colour temperature if needed. Normally this should only be attempted as a very last resort if other adjustments cannot correct a colour cast.
Interestingly, some of the latest NEC/Mitsubishi monitors feature a sRGB colour space button, high brightness and six-axis colour adjustment rather than just RGB. These models are recommended for photo-editing, I am certainly thinking of trying a 19" CRT version.
The Matrox and ATI graphics cards also have colour balance adjustment controls using the software supplied.