Question: The monitor for my desktop hums/buzzes when a have a white background with a lot of black text maximized. I'm sure it would do it in other cases but this is the most obvious. I usually hear it when I am looking at a text file in an SSH client. 

What causes this? Is it clear that it is time for a new monitor?

I can provide details about my hardware if that will help.

It's a Dell 2001FP.

Answer: 
LCD monitor's backlight is a fluorescent tube (The [specs](http://support.dell.com/support/edocs/monitors/2001fp/EN/specs.htm) specifically say CCFL). The backlight's power inverter sometimes hums, or makes other noises. This is only indicative of low quality of the some of its components, usually it **does not** mean the monitor is about to fail soon.

How to fix
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Adjusting the brightness nearly always helps to at least reduce the humming, or change its frequency to make it less irritating. The exact best brightness level can only be found by experimentation. E.g. start with 100%, reduce one step, wait 2-3 secs and listen... You'll find a couple of brightness levels that will sound better than the rest.

Unfortunately, there is not much else you can do about it.
If its a CRT, try degaussing it (it'll be an option upon the on screen menu built into it usually). That sometimes used to help for me, anyhow.

If its an LCD, try lowering the brightness setting to 60% (which is usually easier on the eyes also) as they usually leave the shop cranked right up.