Being 5'8" myself and looking at the BMI charts, your goal is realistic. But it's best to focus on how you feel and how you are eating, and not just some magic number.
I don't know where my weight is going to settle, either, but I'd like to be between 150 and 155 mostly because I don't think I'd be able to maintain it any lower than that. I also like the way I feel eating this way and have found wonderful yummy healthy food to eat. I'm in this for the long haul and mostly for health reasons. I have weeks where I don't even think about the numbers on the scale, but since the holidays I've been weighing more trying to undo the little bit I gained.
I think many of us here are struggling to be healthy and happy with our bodies, so you've got lots of company! My main goal is to be healthy and find a place weight-wise where my body, exercise, and eating are at peace.
Restart : 1/8/13
Restart Wt: 184.4
Round 1: 1/5/09
Beginning Wt: 191.6
Goal #1 Met: 160.0 7/09
Goal #2 Met: 155.0 3/10
Ultimate goal: 150-155 without having to kill myself with exercise or give up chocolate, ice cream, or wine!