I have a new Western Digital 80G external drive (39 bucks after rebate from CC, couldn't resist), and I'm wondering how anal I should be about powering it down at the end of each day or work session, like I do with my primary hard drive. The reason I ask is, after I un-mount the drive from my desktop, the drive stays on; pushing the Power button makes the button blink a few times, but it doesn't actually power off until I detach the AC cable.