This most certainly should work. I have one hooked up to my G5 tower and it works flawlessly. Toast sees your internal drive as the "default"; you just need to select your Sony burner as the "read from" or "burn to" device. When burning in Toast, you select the device in the bottom right hand corner, to the immediate left of the big burn "button". If you click on the little asterisk symbol, you'll get a device selector menu, no matter which mode you're in.