Hi, I have an external 750GB hard drive that I previously formatted as FAT 32 because I wanted to be able to plug it into Windows computers as well. I was not very thoughtful at the beginning and I just created one big 750GB partition. I currently have 450GB used and about 300GB free. I would like to create a new partition in the free space without losing the data I have in the disk, and format the new partition as Mac OS Extended to use it for Time Machine backups. Presumably Disk Utility can do it, but when I go to the "Partition" tab it says "This partition cannot be modified" and the "+" sign below it is grayed. Can anybody help me repartitioning my drive without losing my data? Thanks!!!