Comment two words: Universal Binary (Score 1) 467
With a new macbook pro, you'd be getting iLife '06, including the newest version of garageband, which is a universal binary.
Most real world tests (performed on the intel iMacs, not macbook pro's, obviously) suggest Rosetta runs powerPC native apps at about 50% native speed. But Universal Binary apps run a good deal fast (I'm seeing 20-50%ish, depending on the app).
gekko