I just bought a Western Digital Passport 250GB hard drive. I'm using it to store all of my movies that happen to be in .MP4 format. I never formatted to reformatted the drive. I just plugged it in and started adding my movie files to it. If I wanted to watch these movies at my girlfriends house, would I be able to take the hard drive and plug it into her PC and watch the movies from there? Is that possible? Should I have formatted or reformatted the drive before adding the movies? Do I have to format/reformat the drive to watch the movies on my girlfriends PC? Thanks!