Using a computer regular has some health risks.  From just getting dry or red eyes to actual wrist and back problems.  Avoid health problems with these tips:

1. To avoid eye strain, use the same amount of lighting you use when reading a book.  Lower the brightness on the monitor if necessary.
   
2. The monitor should be 18" to 30" away.  The top of the monitor should be at or just below your eyes.
   
3. Keep elbows and forearms as parallel to the floor as possible. Use a comfortable wrist pad under the keyboard and mouse.
   
4. Use a height-adjustable chair with good lower back support.  Keep feet firmly planed on the floor.
   
5. Get up and stretch regularly -- at leave five minutes every hour.