Whatever you choose, read the Digidesign website closely--particulary the detailed sections on system requirements. If you get a Mac don't be under the illusion that noting can go wrong. It's a computer and bad things happen, particularly under the demands placed on the system by audio recording. I've owned too many Macs (Performa, G2 225MgHz, G4 450 MgHz, Flat Panel I-Mac, G-5 2GHz I-mac, and several i-books) and trust me, shit happens! So, while your shopping for your new G5, make sure you invest in a copy of TechTool or Disk Warrior. Load the Disk Utilities application in your dock so you can access it when all hell breaks loose and pick up a copy of Ted Landau's book OS X Help Line. It's big, it's yellow, it's fatter than a small stack of bibles, and it's a valuable resource when you are faced with something sinister like the "blue screen of death" or it's less troublesome counterpart "the spinning pizza wheel."