Wendy, I am also finishing a basement and I have decided to nail a "smooth edge" around the perimeter of the room, then put a good underlay down, then carpet. Smooth edge is a 3 foot strip that nails to the floor, then the carpet is "kicked" or stretched to it and nails on the face of the strip holds the carpet in place. You can buy smooth edge that is made for concrete floors, but I am leary of hammering nails into concrete. I would rent a hilti or remington nail gun to secure the strip to the floor. Choose a good underlay, it will prolong the life of the carpet.