I'm not sure about putting an SSD into a G5. They are very outdated nowadays. But there are still some great things to do with them But back to the original topic, Microsoft really needs to step up their game (literally). Its really not right for them to call it an Xbox 360 game if its running on a mac.
XenonOS is running on PPC Hardware, the G5's happened to have this hardware available at the time the 360's were still be designed / manufactured. It gave the developers a head start. http://imgur.com/a/5Ko5W
Wow this is old. I wonder if it would be safe to say the very first steps for the making of the console.