For a while I was running linux and windows on the same computer but on different hard drives. To switch systems I shut it down and used hard switches (special

For a while I was running linux and windows on the same computer but on different hard drives. To switch systems I shut it down and used hard switches (special hardware in a disk drive slot) to power off/on the right hard drives. This way you only need one computer, but can have multiple completely separated OS'es. Of course, this doesn't work for laptops.