If you eat a proper balanced diet with adequate fresh fruit and vegetables it should not be necessary to take any vitamin supplement. Your vitamins intake will be OK. The main thing for adequate bone strength is to ensure your calcium intake is adequate. The easiest way to do this is by including dairy products such as milk and yoghurt. For most people skimmed milk and low fat yoghurt are the best options as they will fit in with both normal eating patterns and most weight loss diets. At age 15 you should be consuming 1300mg of calcium daily (the highest level of your life) and this would be supplied by consuming a pint of milk and a yoghurt daily.
However, if you suffer from lactose intolerance you are best advised to use non-dairy products. Rhubarb, spinach and sardines are possible alternatives that have high calcium content.
and to go with danielle, shes right, vitamin D is needed to absorb calcium. it is one of the easiest vitamins to get into your body. all you have to do, is expose yourself to the sun. haha simple being out side and you make vitamin D haha :)
I'm not sure what specific vitamins are good for bones, and strength, but I do know Womens 1 a day vitamins are good for all different kinds of things.
For bones you need vitamin D and vitamin K - they aid calcium absorption.