Here is alink to an Xpen. This is what I use when the pups get older. To protect my carpet I just got some large pieces of heavy duty vinyl and sewed them together to place under the xpen. I bought 2 sets with six panels each and it makes quite a large area. I will post a video of it in the video section so you can see the little ones in action.
http://www.petedge.com/Pet-Yard-Exercise-Pen-ZX191.pro