Using GPS & Laptop

I use to use Delorme until Garmin bought them out and can't buy it anymore. Does anyone know of a mapping program that I can hook an external GPS antenna to my laptop and I can see my car driving on the road? I usually load my waypoints to my GPS and pick which one to goto. Then I can view the way points on the bigger laptop screen as I drive by them. I use this for metal detecting thanks... I asked Garmin for a suggestion but they couldn't give me one so Im putting out to the people... Thanks ahead of time...

Mike