I know this is off topic, but I thin it might be relevant. There has been much discussion as to the one 'upgrade' policy in the Vista EULA. However, if I had a household with 4-6 iMacs running OS X (especially if they all have the same configuration), could I use a single upgrade OS X to upgrade them all? Not having read the OS X EULA, I would think not. but since OS X is tied to specific Apple hardware and does not require a key or activation, how would Apple know that one disk has upgraded several computers?