Motor
Most standard treadmills have motors that run around 2.5 CHP, which stands for continuous horsepower. This will allow you to walk, jog or run an average amount.
If you plan to use your treadmill often, particularly for jogging or running, you may be better served with a stronger motor, generally 3.0 CPH or higher.
And if your treadmill will only be used for walking, you can get away with a CPH of less than 2.5.
If you want to watch TV while using the treadmill, keep in mind that more powerful motors will run more quietly.