Not really a good comparison given that OSX 'upgrades' are available on a yearly (sometimes bi-yearly) basis. Which is about the same time span as Service Packs

Not really a good comparison given that OSX 'upgrades' are available on a yearly (sometimes bi-yearly) basis. Which is about the same time span as Service Packs which are free. And you've still paid for the hardware, which is where the price is wrapped into, since about Snow Leopard. Not saying it isn't good (I am a half-time Mac user). But calling it 'free' is not entirely the case. I used to get pretty annoyed at having to pay for a new version of OSX from 10.2-10.5 every year or so.