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Desktop manager is available for MAC so moving contacts and other items is easy. As for moving the media card, it may not be possible until formatted due to the security employed by BB. You will need to copy all the data to the Pc then using DM move what you want to the new BB and delete the rest. If you think you will have issues with some of the photos on the BB and do not want to have them on your Pc then you may reconsider having ATT do it. They will us a PC also and virtually everything is able to be seen.
a RIM help file
http://www.blackberry.com/btsc/micro...0%201125527198