First off, my thanks to the HDD gurus that come in here on a near-daily basis and answer the complex, if not repetitive, questions that many of us post. Secondly, I have what I hope is a simple question. After reading posts in this thread, and GoldenMacKids treatise on HDDs, I ordered and received a WD My Passport 500GB Mac External HD. I've used it for about a week as my Time Machine destination. Here's my question. Do I keep the Passport plugged in all the time? I can't tell when Time Machine is doing its backing-up, and I haven't figured out how to go into TM and tell it to go ahead and back-up. I went into Finder to "eject" the Passport, but when I clicked on it, the Passport is still spinning. When do I know it is safe to disconnect it? Thanks again !