Mac OS X can only be installed on Apple hardware. It would be against the EULA to do otherwise.
As for the differences between OS X and Windows, the core concept of a window, icons, menus, and a pointing device is basically the same. Where they start to differ is in file management hierarchy, how they deal with volumes/drives, and the use of menus. I would gather it would take a Windows user open to using Mac OS X about 10-15 minutes to accomodate himself/herself.