Lost all ratings, playlists and how frequently played

Hi
I recently bought a new pc. I installed iTunes and copied the old iTunes folder containing my music from my old pc to the new one. The problem is the new pc says it has over 9000 songs on it and shows no ratings or how frequently played and also my playlists arent there either. However when I plug my ipod in it says the ipod has slightly less songs on it and a few of the ratings appear on the pc. All of the ratings, frequently played and playlists exist on the ipod. Can anyone tell me how to clear all info on the pc and sync the ipod with the pc so the pc shows all the correct statistical information ?

Thanks
Simon