You should check out the thread in the I Can Relate forum called A Healthy You. Lots of people on the same journey.
I'd advise you to change your thinking from diet to lifestyle change. The diet mentality just causes you to yo-yo.
There has been a lot of talk lately about weight training being better overall for you than aerobics, but I like to combine bo th along with yoga. I currently workout at a local YMCA. I like taking the classes, as it keeps me in a routine. I take spin, weight training and yoga two times a week each. If you prefer to workout at home, Womens Health magazine has some good books. The Big Book of 15 Minute Workouts is great--everyone can spare 15 minutes a day. Most of the routines are done with hand weights; I only use dumbbells, as I don't really have room for a weight bench and barbells.
If you perform the workouts as outlined, you will get aerobic benefit as well as weight training benefits, but you can combine it with some form of aerobics. Zumba is a great cardio workout and it can be fun (if you don't have wooden hips like me )