re-activation/authentication worries are a thing of the past with OS X. the software that comes free with OS X varies, depending on machine and whether one buys the OS X in a box for approx $129 U.S., hence it's somewhat less expensive for the full version than is vista, which is allegedly a copy of OS 10.2 and 10.3, and imitation is the most sincere form of flattery. can hundreds of M$ software engineers be wrong in their choice of a model? there are, however, nearly a dozen exploits of OS X, including approx. 4 "concept" exploits (e.g. the latest bluetooth thing), vs. ..... hmmmmm... I dunno .... sumpim like 650,000 against windows. I must say that I shudder at the thought of havinta worry about viruses/worms/trojans/rootkits/ spyware 24/7.