Leopard as provided with Macs is more than just Leopard. It includes iLife, and a hardware test all free as a means of testing the machine for hardware, directory, and permissions issues. Leopard as a stand alone retail installer does not include iLife, (except for iTunes), nor does it include the hardware test. So consider what you get as bundled with your Mac, more than if you had purchased them separately. I think one should consider this a free benefit, not a separate licensed software.