It also means don't share the entire of C:, since you'd end up sharing the Windows folder underneath it. I'd also suggest not sharing the Program Files folder, (not least because many hubs ban you for sharing installed programs for a start), but also because Windows and other programs store there own settings in there too, including possibly sensitive data so would be equally as bad as sharing the Windows folder. Basically, make sure you know exactly what you're sharing, every single file, to be safe