Looking for good prevention? Try Workrave application. It's a free reminder application to warn you if you had worked too long without a break. So far I've been using this application for months in Windows 7 and it works. What this application do? Basically it just a reminder application, you can set the work hours interval to make you take a break. For example, you can set Workrave to remind you to take a break every one hour work using your computer. When you don't use your computer the countdown timer will pause so you don't have to worry about how long you've been really using the computer. You can decide how long the break you wanna take, just a micro break or you need a coffee break? Will you need to postpone your break? You can set it all. I found this application so simple but yet complete function to warn me to take a break. Here is the application's introduction written in the site.
Workrave is a program that assists in the recovery and prevention of Repetitive Strain Injury (RSI). The program frequently alerts you to take micro-pauses, rest breaks and restricts you to your daily limit. Please refer to the feature comparison for a complete list of features, and how the program performs with respect to other programs on the market. The program runs on GNU/Linux and Microsoft Windows. http://www.workrave.org/So...what do you wait for? Download it, install it, setup it, and try it yourself the benefit.