My laptop is getting close to having a full harddrive. I'm looking to get anywhere from a 100 to 200 GB of external hard drive. I would use it as a back up. i'm scared of the external hard drive some way or another failing, and losing a lot of stuff that i'd probably delete off my laptop as soon as i back it up. so i'm wondering what are the best brands for hard drive, and least likely to f up?