I'd have to put them in this order: 1. Mac OSX Leopard 2. Linux 3. Windows XP (runs through bootcamp or parallels on my MacBook Pro) 4. Vista Vista is just plain terrible though, it uses up way too many resources and still doesn't achieve the friendly experience Leopard gives you. I used to have it as my Windows partition but then I wiped it and installed XP on it to play Steam games. I also have Linux running here and love it, though it's a pain to set it up in comparison to OSX.