I fail to see how it can be considered "piracy" if you purchase a copy of OSX and just happen to install it on a PC rather than a MAC.
re piracy
If you buy the install discs and use them in violation of the EULA that by definition is an act of software piracy but not too egrigious. However, I was more thinking about the BitTorrent OSX files being feverishly downloaded by real pirates who have no intention of ever paying for it and who want to install it on unsupported computers.