Kim, I don't handle the private server -- I have a colleague that rents space on hers to me. I am so technologically behind that I wouldn't even know where to start, unfortunately. But, I'll try to explain it. It's a dedicated server that I log in to with Remote Desktop. I don't know if there's a limit to how many people are on there but I don't think so. Clients get logged in directly to the QB file and only have access to their client folder which just contains their QB data file. I have access to the entire server and can store files, and do other stuff...I can use it just like it's my desktop computer if I needed to. For safety/security reasons the clients only can access their data file in QB.
The online hosting companies I only had access to the QB program and data files.
Hope that answers your question...if not let me know.