Sync Imac And MBP

[Toughie]

hi im new to the forums and to macs so go easy, i purchased the 21.5 i3 imac late last year and love it. Cant believe it took me so long to be convinced to go to a mac. Im planning on purchasing the new macbook pro as soon as it comes out and was wondering if i would be able to sync them together as will use imac at home and macbook at work or at my girlfriends house. Mainly itunes,photos,email and documents etc. or would everytime i import pictures or music to my imac have to do the same to the macbook. I know of dropbox but not sure i know how to use it to its full potential or if it can do what i want. If there is know way of doing it thanks anyway.