Cardigans and Pembrokes are quite different from eachother. I do not have experience with any of the breeds you are considering but after many years of studying dogs, I know that Cardigans don't enjoy kids as much as Pembrokes. You can find more info at these sites:

http://www.puppdogweb.com
http://www.dogbreedinfo.com
http://www.google.com
http://www,gotpetsonline.com

Hope I could help you a little bit...