There are two types of cardio training- moderate long-duration, and interval short-duration. Both have their benefits, and should form part of your routine.
Moderate long-duration is brisk walking for anywhere from 30 minutes to 1 hour. This type uses glucose in the bloodstream, glycogen in the muscles, and fatty acids in the bloodstream. Because you are going moderately, or high moderately, you are not burning a high number of calories per minute, so you have to walk longer. Because you are not walking intensely, your cardio vascular system can keep up the pace for a longer time. This type builds endurance.
Intensity interval cardio training is of shorter duration because you are placing a high demand on your respiratory and cardio vascular system. You are also exercising your system to respond to a fast high demand. Your intensity should build as you become more conditioned. Your body creates energy in the same way, but because it is more intense, you burn as many calories in a shorter time. Intensity interval cardio should last from 20-30 minutes, and should be done no more than 3 times a week, unless you are in a specific training program.
Here is a chart that might be useful:
Intensity Time Calories burned
Low / light 60 minutes less than 3.5 per minute
Moderate 30-60 minutes 3.5 to 7 per minute
High / vigorous 20-30 minutes more than 7 per minute
I have never done Tae Bo, but I think it would place in the intensity range.
Hope this helps...
Do or don't do; there is no try (Yoda)