The standard form of Tabata is 20 seconds of work followed by 10 seconds of rest for 8 rounds. You should be going at maximum intensity, and not at a leisurely pace.
A six week study by Tabata et al compared a tabata group with a 60 min spin cycle group. The spin cycle group spent 300 minutes per week on their bikes and saw no improvements in anerobic capacity (not using oxygen) and less than 10% improvement in aerobic capacity (using oxygen). The tabata group spent less that 20 minutes per week on cardio and saw a 28% improvement in anaerobic capacity and a 14% imporvement in aerobic capacity. It's clear which form of training is best for gaining results.
Stop wasting time on cardio machines! There is no need to spend an hour on an elliptical when you can accomplish more in 4 minutes with some simple exercises. Here's a very fast example of a 20/10 tabata session using our rope and some weighted burpees. Check it out and give it a shot!