I'd think that using http://eol.jsc.nasa.gov/HDEV/ would be the better option, as it gives you an indication on where your looking at. Cause some should also combine it with that ardunio project that triggers some form of indicator whenever the ISS is overhead or visible.
EDIT: the ISS was approaching Grand Rapids, Mn as I was posting that.
EDIT: the ISS was approaching Grand Rapids, Mn as I was posting that.