It has been a few weeks trying to figure it out this problem, my new Western Digital drive model WDBACX0010BBK, 1TB USB 3.0 was working fine in MAC OS X snow leopard but when plugged into windows 7 the operating system did not recognize the drive. not even appearing in Windows Disk Manager.
Originally I thought it was related to the drive being formatted as MAC OS Journaled, so I re-formatted the drive as FAT, but that didn’t work either.
The Solution: easy as it sounds: run windows update, I had my machine configured to not to update automatically and missing some security and windows updates that fixed this problem.
(Windows 7 X64, and MacDrive 8 Installed )