Difference between canon powershot 8.0 mp (sx100is) and canon powershot pro series 8 mp (s5is)?

I have a 6mp canon powershot that I like very much. I was thinking of going to a digital slr because I want to be able to get really good and clear pictures of small items, but I don't know if i am ready for that yet. But I am also considering the 2 above cameras which would also give me stabilization, PICTURE TAKING SPEED (so lacking in my camera) and face detection. Can anyone tell me which of these cameras is better? Also should I be looking for higher mp's? Obviously, I am not an expert so I need all the help I can get!