The ergonomic keyboard is a recent development. Manufactures designed this keyboard to reduce repetitive stress injuries such as carpal tunnel syndrome. This is a serious injury which occurs when you use the keyboard over long periods of time. As more people use PCs this injury is becoming more common.
Ergonomic keyboards reduce the stress on your hands while typing. They do this by splitting the keys into two sets and arranging each key at the correct medically prescribed position for each finger and angle for your wrist. This allows you to position your wrists more naturally over the keyboard.
If you plan to spend hours on your keyboard, you should do all you can to alleviate the stress on your hands while typing. The important thing to remember about keyboards is to find one that is comfortable for you. With the variety of ergonomic keyboards on the market, this should be easy to do.