Sorry Lixy, you've caused me to get up on my diet soapbox.
One pound of fat weighs exactly the same as one pound of muscle. The difference is in volume. One pound of fat will take up considerably more volume than one pound of muscle.
I'm also not a huge believer in the exercise for weightloss. To lose one pound you must get rid of 3500 calories, somehow. The most I've burned in a strenuous workout is about 600 calories. Don't trust the readouts on gym equipment they are grossly wrong. Exercise will help to tone and reshape your body as you lose weight.
If you are looking to tone up in the midsection I recommend googling "core exercise" - there is so much more than just straight crunches that will work the midsection.
No one has mentioned water yet, make sure to drink no less than 48 oz of the good pure and clear stuff. Nothing added to it, just plain old water.
A website that I've found that seems to have a good diet plan, calorie counter, and a plethora of information is
www.sparkpeople.com
Do make sure to increase your intake of vegetables and fruit. Try to stay away from the starchy vegetables. Also foods higher in fiber will digest more slowly and help stave off the hunger longer. Make sure to keep some fat in your diet, it's essential to digestion as well as the ingestion of certain vitamins. But try to stick to healthy oils - olive, sunflower, canola.