Ah, thanks. I think that's it, Roger. I don't have a Security tab. I'll try that out. Thanks guys.

*edit*
That did it. Before getting to the last point I was stuck at, I'd also made two other mistakes and corrected them. First, I tried to share the whole documents and settings folder, which you can't do. Then, in a similarly unallowable move, I tried going in and sharing each user's folder separately. That only works for the user you're logged in as. I then went and logged in as each user and shared their folders.

And believe me, I understand that this is in no way secure, but this is how the family wanted it.