I have no knowledge of the Atkins diet, but both of my parents used the South Beach diet with great success. My mom went from a 12 to a 4 or 6.
I think the key to weight loss is to set realistic goals and not get discouraged. Losing weight quickly may not happen for you; it doesn't for many people. Just keep exercising and making smart eating choices.
I like to use
FitDay - Free Weight Loss and Diet Journal to keep up with my daily food consumption. It really helps me
Good luck and keep us updated on your progress!