You will need to use ethernet or firewire to do the transfer and make sure you only check off applications otherwise it will bring over her user accounts and what not.
While Migration Assistant would work you probably don't need to use it. When you boot the new MBP for the first time Setup Assistant will start and will ask if you are moving from another Mac, simply answer yes and follow the on-screen instructions and it will be done as the MBP boots for the first tim. You need to have a Firewire cable to connect the 2 computers together, if her MacBook has FW800 then it's a simple matter of using a FW800 cable, if her computer ONLY has FW400 then you will need a Firewire 400 to 800 cable (or adapter) which you can easily find at Amazon. DO NOT use an ethernet cable for some reason they tend to have more problems than Firewire. You also need to think about what you want transferred over, this transfer does NOT give the ability to pick and choose which apps to move, it's an all or nothing proposition! You also need to think if you want settings and data files to be moved too.