I don't condone piracy but I don't see anything wrong with what he is doing. Vista gives the user a 30 day grace period to use the software before purchasing a license.
And please don't come with the "if ...." analogies, now when you can drive an operating system to work every day, or even take it out for a joyride (in the sense that you were portraying it) then you can start using those analogies.
And why would anyone buy a mac to try out an OS they don't even know much about. That's ridiculous.
Edit: Before everyone jumps on me, I am not saying he should be running OS X indefinetly, if he does that then sure he is pirating, but if he is looking at the OS for 10-15 days, then I see nothing wrong with it. If he likes it it would be up to him to purchase
a mac or continue to do what he is doing. What bothers me is the use of analogies that don't apply to the case. Also, nagging about piracy will not stop anyone that wants to pirate from doing so.