Somehow I've managed to get by with 320 GB as my HDD since september 2011. HowI don't quite know tbh. I have a couple of 500 GB portable hard drives. But most of my space is occupied by movies in iTunes. I dislike having to plug in a portable hard drive whenever I want to watch a film streamed onto the TV in the living room. Unless anyone's got a better idea I guess I'll have to upgrade my Macbook's HDD. Is that possible? And could someone point me to a reliable guide please? Also, if I upgraded the HDD would that void my warranty or something?..