I used a 500gig external drive to back up my iMac. By October of last year i had outgrown the drive so I picked up a 1tb drive to replace it, which it has quite adequately. I want to use the 500 gig drive for something else but I'm not sure how to format it. I get two options. To format as Mac OS (journaled) and Mac OS Extended. I'm not sure what either of these mean, or why either would be better than the other. I only want to drag a few gigs of video from my iMac to my Mac Mini in another room. After the transfer, I'll reformat and use the 500 gig drive as my time machine backup on my Mini. Which format do I use? Thanks in advance for your help.