How can I have my Data on my iMac, my iPhone 4, my Macbook Pro and iCloud without duplicating in any one of them ?

I'm really tired of looking to my Address Book and see the same groups and contacts "On My Mac", iCloud and etc... . If I look at my iMac I don't want to see what is on iCloud and vice versa. I don't want to see my iCal also duplicated ... .

I need my informations to be on my desktop computer at my office. I need the same informations on my MacBook Pro on a meeting with my clients. I need them on my cel phone or my iPad. I need them on internet (iCloud) if I don't have any Apple device beside me. But I don't need them duplicated in none of them.

Thanks in advance.

Fredy.