Let me explain this.
For CRTs, it was already been said well.
For LCDs, I need to correct this with information I have gotten form LCD manufacturers I have spoken too:
This is a common mistake, when people say LCDs don't need refresh rates. The truth, they do, but not in the same words though. A refresh rate to an LCD is how many times a second, the panel updates the content on the screen. A lot of LCDs use 60 Hz as it's just basic and just works. However, better LCDs (and oddly enough, Apple LCDs do NOT count), ones made for gaming, use 75 Hz refresh rate, to update the LCD panel 75 times a second to show more of the frame rates in the games.
Generally, if your LCD shows 75, and it works, use it, this means your LCD is updating at 75 times a second, and you would notice smoother motion if you have the eyes to notice it. For example, in the Display properties, select 60 Hz. Move the window around, notice how it's motion is. Now set it to 75 Hz, notice the window now moves around the LCD smoother, as the panel is actually updating the contents faster.
It's sad that Apples own LCDs only use 60 Hz, as they are quite expensive, and my cheap Jetway LCD, can do 75 Hz.
