I'm thinking an external hardrive is meant for back-up only and then you're finished, then you unplug it.. end of story.
But, I'm an avid collector of music and I listen to it on a regular basis. So, that means I'm constantly making WD's MyBook work hard.. by making it's insides churn, and heat up. My other WD hardrive (160GB, not a MyBook) never really got hot or made a lot of noise. To be honest, my other hardrive was much faster and probably performed better overall! I've heard it's because the MyBook writes/reads slow.. could this be the case? It came with a FAT32 filesystem and I decided to change it to NTFS because I've heard it's safer too. So far, I noticed very little speed boost.
Anyway, with all these reviews and comments about data failing on external hardrives (USB/firewire).. I guess I have to be careful with mine? lol, and also my dad has a Lacie external hardrive.. I don't think it has a cooling system (fancy fan) either. But, I've read reviews about it overheating. In this case, I have personally used it for long periods of time and felt it to be very hot afterwards. If you're caring around a lot of data.. even that is at risk. Backing up a back-up drive seems a bit funny, but I'm beginning to believe it really IS necessary. You never know what's going to happen!