After HOURS of fighting this error, uninstalling/reinstalling drivers, mucking with my registry, restarting, blahh, blahh, blahh... I finally ran across a post that mentioned trying another USB cable. This sounded more crazy than not, but I was desperate at that point so I went for it. Low and behold, my device installed as expected.
Lesson: USB cables can go "BAD" (perhaps a damaged connector) and give you headaches.
Thanks to THIS post for the suggestion.