Looking for guidance in building a new system

Hi I'm new to this forum. I'm not lazy I have been resaearching at various websites and wilkapedia to try and find out how I can build a system and install a retail copy of MAC OSX Leopard. Is any of the intel motherboards that are SSE3 complaint sufficient for starters.
My 2 most confusing things are which motherboard to get and how to get LEO to install on a PC.
I have taken apart at least 3 different macs, including an all in one eMac, and got it to work after upgrading some components. So I have no worries building the system. I just wanna make sure I am buying the proper equipment.

Thanks for any help!