Hello, I just received my 1 TB external drive in the mail today. I plugged in the AC Adaptor (3.5'' form factor) and USB 2.0 cable and it was recognized by Time Machine almost instantly. I closed the prompt, formatted it as Mac OS Extended (Journaled) and began backing up. I was really pleased with how smoothly everything went, I just have a couple of questions about Time Machine itself. I do not want to leave my external drive plugged in and have it back up every hour or at any interval for that matter, so I switched Time Machine to "Off" before I unplugged the drive. It says that Automatic Backups are now off and I plan to plug it in weekly or biweekly to continue backing up my internal hard drive as it gets filled up. Will Time Machine recognize the fact that I did a backup today and only backup the files that are missing from the current backup if I backup next week, even if it's not plugged in all of the time? Also, when I was backing up my internal it didn't account for and back up about 5 GB of space that is filled up on it. Would this be because that is the space of Mac OS X itself? Thank you.