I don't have an answer for you, but I will at least chime in and tell you that you're not alone in this dilemma. G5 w/ PCI cards here, wondering where to go next. I have also considered the hackintosh route, which you may want to look into. There has been a little bit of chatter on the forums, too:
http://duc.digidesign.com/showthread.php?t=239687
To me, worst case scenario for the hackintosh is reverting over to windows. same some $$$ !