Apart from the size of individual files being lower on FAT32-formatted external HDDs, what's the difference? I'm asking because I've just bought a Western Digital Passport Elite 320Gb USB2.0 external HDD and started backing up the home Windows XP laptop (using the SW supplied with the HDD) BEFORE re-formatting to NTFS... Which I was told to do by a (usually) knowledgeable colleague - and I forgot . And it's now an hour (and 32Gb - damn those Apple Lossless files!) later and it's still backing-up... and I'd rather not have to go through it all again; which I assume I would have to do if I re-formatted.