The 404 Tech Support website tries to cover many aspects of using computers correctly. Between finding the right tools for the jobs with excellent freeware or fixing bugs or creative workarounds, you can find it all. Another part of using computers correctly comes down to the physical aspects; an ergonomic setup for computers and healthy computing habits can reduce repetitive stress injuries (like carpal tunnel), fatigue, and other problems associated with sitting in a bad position for a long time.
Fortunately, the Comfortable Computing Initiative is looking out for our best with a few resources. Not only is there a ton of information about the ideal workspace layout for you, but there are also tools to help you make that workspace.
The workspace planner tool allows you to see measurements and heights of where things like your monitor, your desk, and your chair should be. Just enter your height or click on the bar above to see the calculations you need to know.
Visit the Comfortable Computing Initiative site for more information and great resources to help prevent repetitive stress injuries and have a more comfortable work environment.
Two links from their site has to do with healthy routines that you should incorporate into long work days.
This poster (PDF) is handy to hang inside cubicles or near work areas to remind yourself or co-workers to stretch every so often.
Another resource is the free WorkRave Software. This little application would be installed on your work computer and is designed to help recover from RSI. It can pop-up little reminders to stretch at specified intervals. It interrupts your work to remind you to take a micropause. It also guides you through some exercises and stretches you should do for your health. You can see screenshots of WorkRave at their site.