You can run OS X on an Athlon, yes. I've done it on my computer. It had loads of driver issues, but I think if you spec'd a PC around it, you could probably resolve most of them. But it's not just Linux really. That's kind of like saying WindowsXP is just DOS underneath. It's based on Unix, but it's far from open source And I think the reason Apples are ace is because they only allow OS X to run on the proper hardware. It's kind of an all-in-one solution that works really well and the hardware and software are optimised for each other. You will, apparently, be able to run Windows on the new Macs. Throw away your PC