What size screen do I have? Computer monitors (AKA display or screen) are measured on the diagonal. There are two kinds: cathode ray tube (CRT) or Liquid Crystal Display (LCD). A CRT (like an old TV set) is a really big and heavy thing. If you measure it and find the diagonal is 18″, you really have what is called a 19″ screen. The same rule of thumb (add 1”) applies to virtually all sizes of CRTs.
LCD screens are actual diagonal measurements. LCD screens probably will not last as long as CRTs. If you buy one, make sure it has LED backlights in it instead of a fluorescent back light. LED backlights will last much longer than the fluorescent type. They are likely brighter and will produce a better image too. Virtually all LCD screens are what are called “Wide Screen.” That means the ratio of width to height is 16×9 (some may be even 16×10). All CRTs and only old LCD’s are the older 4×3 ratio. A 19″ 16×9 screen has much less height than a 19″ 4×3 screen. If you want the same height in a wide screen as a 19″ 4×3, you need buy a 22″ LCD.
Should I replace my CRT? If your CRT takes up most of your desk, Yes. However, the quality of the image is not necessarily any better. CRTs last longer, but they also use more power. So LCD screens are more “green.” New pretty nice LCD screens run around $130 these days. There are important differences, so ask someone to advise you.
Consider CRT screens to be hazardous materials. They have mercury in them. Please ensure they are properly disposed of.
There are two “standard” ways of connecting a screen to a computer – VGA and DVI. The VGA connector has 15 pins in three rows. In a new screen, you want DVI and may need to have VGA as well to connect to your current system. Your next system may need DVI. You also want to ensure the DVI cable comes with your new screen so you do not have to buy one separately. If your system has both types of connectors, DVI will give you a broader choice of resolutions and possibly a better image. Do not buy a monitor unless it explicity says LED (as well as LCD).