I just checked out an online calorie calculator to maintain weight. For a women your height and weight (for someone having a moderate activity level) you will need to consume around 2700 calories to MAINTAIN weight. If you were going to be conservative and lose 1 pound per week, you would have to consume 2200 calories a day (3500 calories = 1 pound of fat, 500 X 7 = 3500). If you wanted to lose roughly 2 pounds a week, then you would have to eat around 1700 calories. Again, this is for someone with a moderate activity level.
I would think that at least for the first 3 or 4 months you should target around 2000 calories a day and focus on being active. Its always best to go slow and steady! Once that the plateau hits (and it always does) you can try lowering your calories a little bit more.
***edit**
I should point out that online calculators can often be in error. Alot depends on how much lean muscle mass you already have and on your age. The more muscle you have, the more calories you will burn and the more weight you will lose (ie, you need more calories to MAINTAIN. Also, age is a factor. The older you are, the less calories you need (metabolism slows with age, a cruel fate that explains why we add a pound or two as we get older). I've used the hypothetical age of 25 for the calculations I did.
Is this too much info?!
Matt