I saw a similar
thread on this subject matter and I started to do some research and I found out that YES! you CAN run almost ANY Apple OS on a PC.
G5 was right by saying you need a PowerPC chip in order to get the software to work but that can be managed.
You will need a few things to get it to work.
PearlPC (An emulator of Apples PowerPC Chip)
OS X .iso (Available from Darwin, apples open source initiative)
A few other files to configure the OS.
I found a very good write up
here
Just a quick warning, I followed the guide and it works.... it actually works! The drawback is since the PearlPC software is still in its infancy stages, it is a little buggy but.... it works! Give it a little time and this will really take off.