Microsoft has released Windows Server 2008 Foundation, which is a flavor of Windows Server specifically designed for very small organizations, with up to 15 users. The cost for a complete solution including hardware will be less than US$ 1000.
The Foundation Server will offer basic functionality such as file sharing, printer sharing, IIS, Active directory, terminal services. The server can act as a domain controller or be a member server. All applications that are certified for Windows Server 2008 standard will work on Windows Server 2008 Foundation. However, the 15 user limit will always apply.
Unlike Small Business Server, the Foundation Server does not have any applications like Exchange Server included with the OS.