You don't need to reformat to change to NTFS.
There is a way to do it by typing something in the start->run.
I don't know what the command is off hand, but I can find out.
no. a terabyte (TB) is 1024 gigabytes. next is petabyte (PB) which is 1024 terabytes and following that is exabyte (EB) which is 1024 petabytes. the command is "convert X: /fs:ntfs" and it has to be typed from command prompt.