Two questions: 1) I'm looking for an external hard drive to use for Time Machine backups on a new Mac. Of course I'd like it to be reliable, etc., but I also want it to be SILENT -- or as close to silent as possible. Any suggestions? 2) Can I use a single, large external hard drive to do Time Machine backups for two different Macs? They don't both need to be connected to the drive at once -- I'd just like to be able to connect it to whichever Mac I want to backup at a given moment. If it is possible, will that require configuring/reconfigurring each time? If it's not relatively effortless, so that I just connect it to the relevant Mac and Time Machine takes over, then I'd probably go for two, smaller hard drives instead of one big on. Thank you!