Hard drives are neither NTFS or FAT, they're just platters of bits. You have to create atleast 1 partition, atleast with Windows, and format that with a filesystem, in your case NTFS was used. You can create up to 4 primary partitions on an x86 PC, if you only have 1 right now you should have no problems resizing the current NTFS filesystem to make it smaller and then adding a new partition to put another filesystem on.