A good quality monitor is essential when trading.  Once you become comfortable with all of the different functions of whatever software package you use, you will find a need to have more and more windows open for the many different functions and information displays.

Monitors are available from many different sources and one of the most important factors when purchasing any hardware is where are you going to get it repaired if it fails.  Also, how long will it be in the repair shop.

From most trader's perspective, the larger the monitor the better as you will be wanting to have many windows open at the same time.

In order to add a lot of windows to your screen you will need have your screen resolution settings at "1024 by 768 pixels", "1152 by 864 pixels", or higher.  a resolution of "640 by 480 pixels" won't hack it. 

Make sure when buying a monitor, the manufacturer's specifications allow high resolution setting of these or higher.  Read the product information very carefully.  Don't rely on a sales person's assurance that it will perform at these levels.

In the following links, go to the search area and enter the word Monitor and start the search.  You will find summaries of many models of monitors.   Also, visit your local computer retailer.  Remember, cheaper is not always better if your monitor goes out and you can't get it repaired immediately.  In such a case, you need to be prepared to buy another monitor right away.