I just got an external hard drive and need some help understanding backups. I just backed up all of my 80 gigs of MacBook hard drive space. I am going to manually back it up in about five minutes. Will it only add the files that I have changed? I also have another question. I download games and other large files to my External Drive from my Mac and then move them over to a PC to play them. What is the best way to reserve maybe 40 gigs for only Windows files? Must I partition so one is a Mac format while the other is for PC? I do have MacDrive, but I don't know if that is something I want to install on many PC's. Thanks.