You need a cable with FireWire800 connectors on both ends, because both laptops have FireWire800, dferigmu. Then start up the PowerBook in target disk mode (hold "T" while starting up), like NOFEER suggested, and it will show up on the MBP's desktop as an external disk from which you can download single files, whole folders, or anything else you've got on that Powerbook, to your MBP, by simple drag & drop. You can upload to it too, BTW.
If, OTOH, you have a brandnew MBP you could also install a fresh Leopard or Snow Leopard on it from the install DVD, and it will ask you if you have an 'old' Mac that you want the data, apps, and settings (as far as applicable) transferred from to your new MBP. Just click affirmative and follow directions from there. Then grab a cup of coffee.
100GB will take from about a half hour to 1 hour. It will tell you when it's finished. Then simply restart your MBP, and you're all ready to go! Everything will be where you expect it to be, with all your apps installed and working. Couldn't be simpler. And saves you countless hours, if not days, of reinstalling everything manually, app by app...