A.B.
I am an interior designer and I work for an architectural firm. I would recommend looking into modern radiant heating (I would not use the ancient one in your slab). Radiant heating these days is not what it used to be, plus it is super efficient and leaves no cold spots in the house. It would be installed over your slab and under flooring. I would not recommend forced air, it is one of the most inefficient systems. Even radiant baseboard heat would be better than forced air. The radiant flooring manufacturer I recommend is Watts SunTouch:
www.wattsradiant.com
www.suntouch.com
Check out my article about radiant heating: http://anvdesign.blogspot.com/2009/01/eco-friendly-radian...