as an old IT analyst and computer maker for decades, I must respectfully disagree with sharpandpointless on text colors and monitors.
As a person with less than perfect eyes, I've been called on to evaluate monitors and site readability for a long time. People do still find that dark text on a white background is easier on the eyes. The photon thing is urban legend. For one thing, the photons "shot" isn't really the case, the phosphors glow. Nothing is really being shot at the eyes.
Here is a small portion of a university study on web site readability, usability and the affect of text size and colors, background colors and textures (I've left out the parts dealing with text size and line length)
>>Background textures and colors can affect the readability of text. For example, Hill and Scharff (1999) found that plain backgrounds produce faster search times than medium textured backgrounds. An important determinant, though, is the contrast between the text and the background -- the more textured the background, the greater the contrast should be between them.
Moreover, textured backgrounds that are subtle at true-color (24-bit) settings, often become very noticeable at lower-color settings (i.e., 8-bit), thereby reducing the contrast between the text and the background even further. Thus, if one is to use a textured background, it is recommended to be very careful by testing it in different color settings.
As for color, as long as there is sufficient contrast between the text and the background, many color combinations are possible. However, most studies have shown that dark characters on a light background are superior to light characters on a dark background (when the refresh rate is fairly high). For example, Bauer and Cavonius (1980) found that participants were 26% more accurate in reading text when they read it with dark characters on a light background. Moreover, a survey by Scharff, et al. (1996) revealed that the color combination perceived as being most readable is the traditional black text on white background. However, it is common for websites (such as this one) to have an off-white background in order to reduce the flicker and glare associated with white backgrounds.
In the Scharff et al. (1996) study, other color combinations that ranked high were white on dark blue and red on yellow. However, one should be cautious in using colors such as red on yellow that are pure or 'saturated.' Saturated colors create visual fatigue and make it difficult to focus on the text. It is best to de-saturate colors by adding white or combining them with other colors.
The least readable combination were green on yellow, white on fuchsia, red on green, and fuchsia on blue. Also, for all combinations, the lighter backgrounds with darker text was considered to be more readable than darker backgrounds with lighter text.
Approximately 8% of males and a little less than 0.5% of females have a color deficit of some kind. In fact, one study found that around 4% of Internet users are visually impaired in some way (GVU, 1998). Thus, it is important to note that different font sizes and font color combinations can have a dramatic effect on the readability of a site.
For text colors, it is important to have a good contrast difference between colors that need to be distinguished. Some color combinations generally frustrate users and make it virtually unreadable for color deficit or "colorblind" users (Nielsen, 1996). That is, for many color deficit users, red, green, brown, or purple may look the same if these colors have the same contrast. Since color deficit users cannot distinguish between a large spectrum of colors, it is therefore advised to strongly contrast the colors (make sure one color is darker than the other) between the foreground and background, as well as between other colors that need to be distinguished (see Wolfmaier, 1999, for a good description of the proper font-color mixture).<<
Trust me on this one - I can detect the slightest "readability" issue. I've studied it at length (as did the company I used to work for when I filed a complaint against them........)