We are at about the same place weight wise, although I gave up the goal of being 120 again
(I am 38 and have 3 kids) . . . I think the South Beach Diet is a great diet but also a great way of life - I have about 20 pounds to lose too but will continue to eat like this after I lose the weight - healthy and easy to do and how I ate when I was skinny anyway! It is also super easy to do when you go out to eat, which I love to do and we do a lot of.
Basically you eat lean protein, veggies and fruits and no refined carbs, which is how we all should be eating anyway I think.
Hope you decide to try it - it has been the easiest diet I have ever been on (and I have been on many in the last 6 years losing all this pregnancy weight!)