Google's done a super good job on search; Apple's done a great job on the IPod.
Whether it's Google or Apple or free software, we've got some fantastic competitors and it keeps us on our toes.
Imagine the disincentive to software development if after months of work another company could come along and copy your work and market it under its own name...without legal restraints to such copying, companies like Apple could not afford to advance the state of the art.
Apple has always leveraged technologies that the PC industry has driven to critical mass - the bus structures, the graphics cards, the peripherals, the connection networks, things like that - so they're kind of in the PC ecosystem and kind of not.