GPS via Tablet pc

just wondering if anyone is using GPS in a tablet pc ? If so is it just a program that is added to a unit that already has a built in gps? I am guessing that a gps for auto or aviation the hard electronics are pretty much the same but there programming is the difference? I am just trying to learn as much as I can so when I do invest in a unit I buy one that has the most use for my life not just for in the plane. Thanks