I also need to help a friend who's trying to see shared photo streams on his Windows 7 PC. We've read all the documentation and troubleshooting tips and browsed answers in these forums -- many times.
He has a working iCloud account, which we verified by logging into it on iCloud.com. We've also installed iCloud Control Panel 3.1, and that seems to be working properly.
The problem is he's stuck at accepting an invitation to a shared photo stream. Whenever he clicks the link to join, he just gets taken to a Web page that says he needs an Apple device to join a shared photo stream. Based on what we have read we had thought that he should be able to join on a PC because he has an iCloud account and a properly installed iCloud Control Panel 3.1.
We know about the public Web site option that the photo stream owners can use, but some people do not like to use this option despite the URL being supposedly unique. We'd really like to just be able to get him to join a shared stream.
Where are we going wrong?