I backed up everything important before I installed. I'm self employed too, and have a G5 and a 15" PowerBook. I just kept a few unimportant projects on to see how they took the change. No problems on either machine yet. I even got QT pro on them both. The HD samples on the Apple site are incredible. Spotlight is soooo cool. And now you can sync mail and bookmarks in isync. Its the best upgrade I've ever seen. So far.