I am most impressed by the fact that you say that the external drive does not show in your System Profiler, under the USB tab. If the drive has power, and is connected to a working USB port on your MacBook, then it should appear in your System Profiler (even if it doesn't appear as a valid device in your Disk Utility.)
Here's one way that I would verify this:
Leave the drive disconnected, and open the System Profiler/USB tab.
Plug in the drive to your MacBook (check that the drive actually has power), then press Command-R, which will refresh the device list. Watch for any changes in the USB listing, even if it doesn't appear to be a CD or DVD device.
Does the USB listing change in any way?
Serendipity is a lucky guess !