Here’s a strange one for you. Just tried to transfer some files over to my gaming PC (new demo for Dragon Age 2) which runs XP from my Vista laptop (which normally works) but my Passport Essential HDD doesn’t show up listed in the Hard Drives section in My Computer. However my Vista laptop does make the sound of the HDD being plugged into a USB port. Also, it works fine when plugged into my XP computer. It also shows up as being installed under the Device Manager and when I check for driver updates it says my drivers for it are up-to-date.