"The vertical refresh rate refers to the number of repetitions per second. A CRT (Cathode Ray Tube) monitor refreshes the displayed image tens of times per second. This is also called the "Frequency Rate" and measured in Hertz.
A CRT monitor with a 60Hz vertical frequency rate means the image is drawn 60 times per second. At this refresh rate, some users may see a brightness variation called "flicker." Higher refresh rates mean less image flicker, and less flicker helps you protect your eyes because even the slightest flicker can contribute to long-term eye strain. International Ergonomics Standards (e.g., ISO 9241, Part 3) for computer monitors, recommends a vertical refresh rate at least 70Hz (higher for larger screens), because eye strain can be drastically reduced at this rate.
Refresh rate has greater effects on CRT monitors, while flicker is less noticeable on LCD monitors, because LCD displays do not have a refresh per second."
I myself use 1152x864@100Hz with my 19" CRT or 1280x960@85Hz, but I prefer the first one.