BES -- Switching from t-mobile to t-mobile

Hello,

My boss has an older Blackberry through t-mobile. I'd say it's at least 5 years old (still has the trackwheel on the side). He's just purchased the T-mobile Curve 8900, and wants to switch all his data to the new device. Is this as simple as swapping the SIM Card, or does he have to go through the BB Desktop application and transfer all the data? Also, we run BES at our work. Will switching the sim card and/or changing transferring the data through BB Desktop application automatically set up his new phone for BES?