To avoid desk-related injuries, you can either redo your office with all the latest ergonomic gadgets, or you can follow these basic rules from homeofficebuddy.com (more tips on the site):

Monitor height: To adjust your monitor height (to avoid neck strain) sit yourself comfortably in front of your computer and look straight ahead towards your screen. Adjust your monitor height until the top of the screen (not the monitor case) is level with your eye.

Distance from your monitor: The minimum distance between you and your computer screen should be measured by the length of your arm. Sitting in front of your computer, raise your arm directly in front of you. Your fingers should be just touching your computer screen. If not adjust your distance until this is so.