I have a 500GB WD MyBook HDD backing up my iMac G5 and MacBook. When I set up the HDD I created a 150GB partition for the MB and 350GB for the iMac. I am now wondering if this is necessary. Can TM back up more than one mac on one partitions? If so, is it possible to merge my two current partitions back into one without erasing the data? Thanks!