I received my WD My Book Studio 750gb hard drive yesterday. I updated the firmware, and connected it to my MacBook. Everything seemed to go fine with the first backup, but I have a question regarding the space Time Machine is showing as available. The hdd is 750gb, and shows 698gb available, which I understand. However, Time Machine only shows like 500gb as usable, so why doesn't Time Machine use the entire 698gb? I did do the erase via the utilities, thinking maybe it came with some stuff preinstalled. Does Time Machine keep some of the space on the hdd held back for something? Or do I need to do something else to the drive to make it all available? Not really a big deal, as I only have about 59gb filled on my MacBook anyways, just kind of wondering. Thanks.