If you type a lot (which this day in age you probably do) then it is well worth having the right equipment to avoid injury while maximizing your performance.
You probably won't end up in the ER but the pain and symptoms can get severe. Here is a case of RSI (Repetitive Strain Injury) so serious they were unable to open doors for 6 months!
Ergonomic is the key word - look for products that conform to your body. Comfort and lots of adjustability is key.
A great computer typing setup should focus on maximizing ergonomics in the following four products:
Important Note! If you're looking for the biggest bang for your buck (only investing in one of these items) I would recommend at least getting a good adjustable keyboard tray. This allows for the most customization and adjustability and will probably make up for any short-comings in other areas.
Here are some suggestions as a guide to purchasing the right equipment for your computer typing setup.