Yep you need a program, I have Tomtom and Iguidance, for me I like Tomtom a little better it seems to be a little more accurate for my area both can be found pretty easy to try out

A lot of people like google and live which are both okay too but use a data connection as well.

Personally I prefer Tomtom, besides great accuracy and super easy interface it has a great voice announce that you can get a bunch of cool voices for (celeberties and movie/tv characters).