Very often Windows is shipped with a PC. As I understand I can't use that copy of Windows on my Mac. What can I use? Would Windows OEM be a good choice? Is 'normal' version of Windows okay for this purpose? If I want to run Windows either via Boot Camp or Parallels does it mean I need to have to 2 copies?
Edit: I'm not asking here whether it's legal to install Windows on Mac. I want to know the exact legal details of that. I am a freelancer and I can't afford penalites associated with illegal use of software.