What your friend is talking about is illegal. It is possible (from a purely technical standpoint) to run OS X on standard hardware (with certain modifications), but this violates the EULA of the operating system. Hardware support would be a pain in the rear, and you wouldn't get any help from Apple. If you want the real OS X experience, buy a mac
It should also be noted that you
cannot download OS X Tiger from Apple - it is an operating system that you have to purchase much like Windows or certain linux distributions.