Well good for you! Four years of course for your undergraduate degree which will likely not be area specific since most advisers would like you to have the full anthropological experience which includes classes in all four fields. They also may not offer specializations. The field of anthropology in this economy is a dying one and finding a school that is adamant about their department is a must. Unless you have a school in mind I would suggest you find a school for your undergraduate degree within your state since out of state fees in colleges can be insane. Private schools don't have this discrepancy.
The most crucial part of your schooling are your graduate years which is a minimum of four, but will depend on how long it takes you to research and write your dissertation and have it approved. DO YOUR HOMEWORK! You will find an area where you would like to specialize in and you must scout out your mentor who will help you on your way to your doctorates degree. My area is archaeology which offers excellent schools in Wisconsin and Michigan, not to mention Northwestern, I'm unsure about forensic anthropology. If you do your homework beforehand on your specific area of study be sure to attend a different university for your undergraduate than your desired graduate school since most universities don't accept their own undergraduates for graduate studies. Unfair, I know, but that's how it is.
Also this is an extremely competitive field so make sure you do very well in your classes and get excellent references during your undergraduate studies.
Good Luck!