This is almost exactly what I did when moving my Girlfriend's account to her new White Macbook, BUT... there are a few things you need to be aware of.
Firstly: Install up to date (ie: UNIVERSAL) versions of all the software you intend to use on your Macbook Pro, to ensure all the apps are running natively and not in Rosetta Emulation (for running PPC apps like on your old PowerMac).
Secondly: Create a Unique Administrator account with default settings on the Macbook Pro. Then remove the duplicate Accounts (which have the same names as the ones on the PowerMac) from your Macbook Pro. Migration Assistant copies the User accounts from one machine to the other, but cannot do this correctly if accounts with the same names already exist on the target machine.
Thirdly: Run Migration Assistant, and use the 'Transfer User Accounts and settings' to transfer the user accounts and all your network settings etc. Check what other options you need when working through the Migration Assistant to ensure you get what you want, but hopefully you shouldn't need to use the 'Move Applications' function.
Now sit back and let it run... you should find it as delightfully simple as we did.
