I have an internal hard drive with Windows 7 Pro x64 installed on it. I know the drive works, because I've booted it up in my PC. However, I have a hard drive dock that I would like to test, so I took the drive out of the PC, put in the dock, and hooked it up via USB to my Intel Mac Mini with Snow Leopard installed on it. The drive mounts normally in SL, and I can see and access all the files just fine. However, when I try to boot to the drive via the USB, it doesn't work. The drive does not appear in the Startup Disk pane (unless I hook the dock to the Mac with Firewire) and when I boot the drive from the Startup Select screen, I get a black screen with the error message, "No bootable device found." Now I know I can't boot XP via USB, without modifying it first, but does the same hold true for the WIndows 7 drive? I read the Apple support article which states that only drives that have use the GPT scheme and have 10.4.5 or later installed on it is eligible for booting from a USB drive. I know this is technically an internal drive in a drive dock, but does the Mac still treat it as an external USB drive regardless?