I have a seagate Momentus 120 GB 5400.2 HDD in a usb case. All I want to know is if i can use it as an internal HDD in my 12" iBook G4(1.33ghz). Is the drive compatible?? The 40 gb one that came with it is just not enough. Also what will be the payoffs? Will it affect my warranty in any way. Also will it reduce the batterry life?