Originally posted by Elwood
Making a copy is illegal, for any reason. Please review the license agreement that you agreed to. By accepting, you are now legally bound to follow it. I hope your second PC is using its own RealFlight CD, and not the CD from the first machine, or a copy.
As was stated before, It is perfectly legal and ethical to make a backup copy of software for your own use.
It is also legal to install software you own on more than one computer, provided it is not used on both computers simultaneously.