A little more info on your Rand McNally GPS unit please? Model and Year?
New Rand McNally GPS systems come on a PC Tablet, To update them you just make sure you have a steady fast internet connection, go to the GEAR tab, and search for updates. It will download them and install them for you. Just make sure you don't leave the Internet Connection Location until all updates have been downloaded and installed.
I only question you because you said you need to update your "card"
EDIT: Older Update info can be found here>> Update Rand McNally SD Card
