That is a very good question and although i am not an expert I think you wieght depends on your comfort and what you think looks good on you, not someone eles idea.
I disagree with the above. There is a healthy weight range. If you are 5 foot and 4 inches according to the body mass index the healthy weight range is 108 - 145 pounds. If you are between this range then you have absolutely nothing to worry about.
I will have to agree with the first responser to some extent. I think people get "caught up" looking at a "chart" that says what is ok and not ok. You have to take in consideration muscle mass, bone, water and fat; a simple scale WILL NOT percentage this out for you.
To know how fit you really are, you should have a fitness assessment done by a fitness professional. Just because your weight is in an ideal range doesn't mean you are HEALTHY or FIT.
A simple chart is NOT enough to determine where you should be as far as your weight.
If I may ask, what is your weight?