I recently bought a MacBook. I'm a big iTunes user and have close to 80GB of content. Since my MacBook only has an 80GB HardDrive, i'm running out of place to store my stuff....Someone was talking to me about an external hard drive but i don't really know what it really is and how it works..does it attach to your laptop or something..i don't get..and do you need to take it with you everywhere u bring your laptop. please help me out..Thanks!