Apple has just place an application on their website that tests hardware to see whether it complies with Aperture specs. It reports whether the program can be installed on the system running the compatibility checker, and if not, why not. My dual 1.8 G5 flunks, but it's because of the video card (replaceable) as does my 1.25 GHz Al PowerBook, but that's because I have only 512 MB of RAM (easily upgradeable). I've read posts elsewhere (digital photography review forum) where the compatibility checker has reported that the program simply will not install on systems more powerful than ANY current PowerBook; e.g., the mirrored doors dual G4s with fast dual processors, oodles of RAM, and video cards LISTED by Apple on the Aperture website meeting that requirement. The exclusion of quite powerful mirrored doors dual G4s (even the newest Quad core 2.5 GHz G5s aren't really THAT much faster using Apple's own test reports) is shameful, assuming there aren't any technical issues. Jim Robertson --