Anybody using geothermal for their HVAC?

Just wondering if it would work out for me. I have baseboard hot water (oil fired boiler) as a heat source and an AC unit in the attic. Could I remove the boiler and have the heat pump installed in it's place? Then somehow heat and cool through the AC duct work through the attic? I also have a wood/coal boiler which is tied into my baseboard heat. I would like to keep that for the colder winter months. I was considering going in with my neighbor to have a natural line run back to our homes until he got a price for $65,000. He was told $125 a foot.