Look into a product called Dricore. It's basically a plastic bottom with little feet, and then a layer of wood on top of it. It insulates the floor a bit, and if you get water in the basement it flows underneath the drycore, saving your carpet. You can then put the low pile commercial carpet on top of it. It makes the floor MUCH more comfortable to walk on as it feels like a "real" floor instead of concrete. It's especially nice in winter if you live in a cold climate.