It is easy to insulate a basement when you are finishing it. You just put roxul boards on the walls, cover them with drywall and paint. The only hard part about this is moving all the stuff out of the basement to do it, but since you have to do that anyway in order to finish it, it is actually quite easy. The floor is harder to insulate but even putting a layer of foam underlay on top of the concrete and then putting in thick carpet will greatly improve the insulation. Before anyone does this though I would recommend installing a sump pump and wiring it into the emergency panel and having a back up electrical supply (either a generator or a battery) because even a small amount of water in the basement would now mean that your carpet is ruined. This happened to us, 3 months after installing a beautiful new wool carpet that cost $3,000. We had to put the whole thing in a dumpster.