My Book Essentials 1TB not recognized by MacBook Pro

Have a 1TB My Book Essentials external drive that I was using on a PC with Windows.  Plugged it into my MacBook Pro running Snow Leopard (USB port) so I could format it for a MAC but it does not show up in Finder or in Disk Utility.

I’ve tried using three different USB ports on the laptop without success.  Western Digital support had no answer for me except to suggest I join and post on this forum.

Any ideas anyone?