This might be a stupid question, and hopefully it's easy to answer. I have a little external-USB hard drive, Western Digital, 120GB. Really convenient, can plug it into any PC I want and it goes. I'm gonna wipe it off and reformat it so I can use it for school though, and at school, we actually use Macs. So my question is: Is there a way I can format it so it works perfectly on both Mac and Windows? Nothing special here, just transferring files. If I want to plug it into my Mac at school, put my work on it, take it home and continue working on Windows, is there anything special I need to do? I use HP USB Disk Storage Format Tool for most of my formatting needs, and it works great. Will just a simple NTFS format do? Or do I need to use a different filesystem or something? Thanks. I'm not a Mac guy.