Uhh... why is this on the Lego Millennium Falcon forum? But anyway, older portable drives will usually come formatted for FAT32. Newer drives will almost always be NTFS.
It is possible to reformat all hard drives. First, check with the manufacturer and often they have utilities to do this (sometimes these utilities are installed on the hard drive when you get it.l) Otherwise you will have to search the net. Note that the Windows format utility will not format large portable drives to FAT32 so you need to get a separate program to do this.