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.
Using a bad setup probably won't send you to 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.