For one thing, the modern Mac rarely, if ever, crashes; if an app craps out, it doesn't bring the whole system down with it. Poser 5 is lightning-fast on my G4 laptop (1.25 GHz), stable as a rock, and looks mighty pretty. And if you want to add a peripheral or a new hard drive, you don't have to spend a week on the phone with some guy in India, hashing out the .exes and other PeeCee esoterica. But they're not for everyone; de gustibus non est disputandum.