I know it's been awhile since the questions was ask, but you can make a "Hackintosh" out of the PowerMac by switching almost all of the parts out. It's a heavy undertaking, but if you're looking for a project, it can be done. Google search "PowerMac Hackintosh", "G4 Hackintosh", "Quicksilver Hackintosh", etc. Also, check out TonyMac's website to see the technical details of making a Hackintosh. http://www.tonymacx86.com
I've used a KingSpec PATA (IDE) SSD in my Powerbook Pismo, and should work great in a Powerbook G4 as well. You may have to do some research first, but I'm pretty sure there's a KingSpec model with a more desirable controller chip.