Most of the difference (but not all) have to do with limitations of joining a Microsoft server domain. Unless you have the Business/Enterprise/Ultimate editions, you cannot join a Microsoft domain, which means you can't access any services the server may be offering, such as shared drives, shared printers, etc. The main item missing, and the way the shares are enforced, is that you cannot participate in the Directory Services, which they now call Active Directory. You have a single userid and password, defined on one of the domain's servers (domain controller), and whenever you log on to any PC which is a part of the domain, you get authenticated by a domain controller server. Since Vista Home Basic cannot participate in a Microsoft domain, you cannot have a global userid and cannot participate in the domain at all. Which of course means that the IT Dept., if there is one, also cannot control your PC -- that's the other half of participating in the domain, they get to control what you can and cannot do on your computer (or the one you're logged into).