Hi. I've tried a couple of different brand name DVD burners for my iBook, and powered both first via USB and then with an external power supply. Neither worked despite the manufacturer stating that they're PowerPC and Leopard compatible. They showed up in system profiler, but otherwise didn't function. I'm wondering whether or not I need to disable or otherwise modify the (functioning) optical drive that came with the iBook in order for a USB burner to work? Thanks.