Either way. A subfloor would make the floor warmer, but you can install the carpet directly over the concrete. You just have to weigh the cost to benefit!

Man I suggest you get Carpet Padding at least 8lb for that carpet. Unless your joints are those of an 18 year old.

A little off topic but, we are finishing our basement as well. I would love to have carpet in there. I am worried about flooding though. In the end I know I will not be happy with anything but carpet.

I wouldn't carpet if flooding is an issue. How about an area rug?

The last thing you want is thick padding under the carpet in the basement. In the event of flooding the padding will act like a sponge and absorb the water. It will be impossible to dry. Mold and mildew will grow in the padding, and the padding will have to be changed. I had carpeting in the basement of a previous house. I had the choice of gluing the carpet directly to the cement floor or having a special thin padding designed for basement installation under the carpet. I went with the padding. In the event of water damage a wet vac can be used to dry the carpet. The only issue I had with carpet in the basement is that it was a pain to vacuum such a large area. I suggest if you decide on carpeting get something with a litte print. We used a tweed berber.