Ok, finally got it! It was the android_winusb.inf file that had to be edited, at least for my Win7/64. I used the USBDeview tool you referred to above to get the proper device-id of the tablet and then put it under the Google.NTamd64 section rather than the Google.NT86x section. Then I installed the driver via the Device-Mgr and lo-and-behold I've got an Android device and 'adb devices' finds it as expected. Thank you so much for your help with this!