Go into the Windows disk manager (Administrative Tools -> Computer Management). Find your disk. That applet will tell you whether it sees that there is a drive connected, and whether it can read the filesystem that's on it.
Also... you think it was FAT? Given that the filesystem is such an important detail, you may want to be sure...
I actually sold my Mac and shipped it yesterday so I can't anymore.. even more of pain that I can't access my MyBook now, feels like a waste of a 1TB drive right now.