What is a good age to take away a pacifier?

I gave my daughter a pacifier when she was three weeks old and while she is not dependent on it, she certainly loves it. We use it in the car and at night and sometimes when she is upset it is really the only thing that calms her down. I know young babies have a compulsion to suck and that that is why they like pacifiers so much. However, I don't really dig the three and four year olds that still have their pacifiers. So when is a good age to take them away? Can it be done easily enough before they are one?