If it's a Time Machine backup or a clone of your old system, you can use Migration Assistant to bring over user data and programs. Migration Assistant is located in the Utilities folder in the Applications directory.
Pondini has great info on the procedures at his site:
It's much better to use Setup Assistant when your shiny new Mac first starts up, rather than wait and do it later with Migration Assistant. See How do I set up a new Mac from an old one, its backups, or a PC? for all the gory details.
It's much better to use Setup Assistant ........
This is amongst the greatest of understatements that can be made. I made the "mistake" of using "Migration Assistant", once....and only once. I credit you, Mr. Pond, for creating a greater awareness of the importance and advantages of Setup Assistant, over anyone else. I think more people reference your articles on the subject than even anything that Apple has created on the subject.
Setup Assistant does everthing you need to make a butter smooth transition from an old Mac to a new one. I feel sorry for those that miss the chance to do it because they are unaware of the consequences when they bypass the opportunity.
Thanks very much.
It's so irritating that Apple ignores all requests to reword the page that comes up on a new Mac, implying that using Migration Assistant is just as good (a bit hard to read on the photo, it says "you can transfer information later using Migration Assistant").
Additional comments at http://www.apple.com/feedback/macosx.html might help . . .