plug n' play

Let’s face it, for dummies like us, electronics can be a bit perplexing. We liked this post on that subject from our Fabulous Forums… 
I have expedition (on a toughbook), but was wondering how I would go about connect it to an external GPS. I have a b&g GPS and radar on deck which attaches to a chart plotter.
Can I use the same GPS and run a wire to the computer, or should I buy a separate one? Also do you guys have any suggestions for the model GPS to buy?
Jump on in if you can help