Which kind of exercise gives the biggest impact in trimming your tummy?

I have read that pilates is wonderful for your abs. I also read recently that it is good for your abs to pull you stomach muscles as tightly as you can towards your spine when you walk.

i think working out for abs is the best excercise to trimm our tummy

I think that anything that gets the heart rate up is good for excess weight around the tummy. Cycling, running, aerobics etc. Rowing I think is especially good as this uses all your large muscle groups. Sit ups are good for strengthening the abs, and toning, but wont see the results until after the excess weight is gone.