I use both a Windows PC and a Macbook computer, and have had trouble finding an External Hard Drive that I can use on both. I tried formatting the drive to Fat32, but that seems to only allow me to move files under 4GB onto the drive from my Mac, which is a bit of a problem when I download a ton of HD movies. I found out about a software called MacDrive, which allows me to format my Hard Drive to a Mac type, but it is also recognized on my PC. The problem is that the software is only a trial version, and I can't find a working serial number anywhere. I downloaded a serial maker for the software, but it doesn't seem to work. Does anyone know what I should do. ANybody have a working serial number, or a different solution of what I should format my Hard Drive to? Thanks for the help.