How can I determine what I should weigh?

Body mass index (BMI) is a measure of the relationship of your weight to height and provides a reasonably strong correlation with the amount of body fat in most people. The lowest health risks for adults are correlated with a BMI of 18.5 to 24.9. You can calculate your BMI using this tool by entering your height and weight: http://bit.ly/A603mH.
 
If your BMI is greater than 30 you may want to set a target of a 10 to 15% weight loss initially and master the skill of maintaining that weight for several months before attempting a further weight reduction.