I have a MacBook Pro running Snow Leopard. I have a Seagate FreeAgent 250 GB external hard drive that I want to use with my MacBook, but when I plug it in and access the hard drive folder, it tells me I can only read the hard drive, not write to it. The hard drive format is Windows NT File System, so does that mean this hard drive can't be used with my MacBook unless it is re-formated?