Multiple Users on a Single OS Requires Microsoft Windows Server Licensing
For applications where multiple interactive users are simultaneously sharing a single operating system, standard Microsoft Windows Server licensing applies. This means that the shared host computer (or virtual machine) runs a Microsoft Windows Server operating system.

In addition a Microsoft Windows Server Client Access License (WS CAL) and a Microsoft Remote Desktop Services Client Access License (RDS CAL – formerly known as a Microsoft Terminal Services Client Access License or TS CAL) are required for each end-user or device that accesses Windows Server.

Also, Microsoft's new Windows Multipoint Server 2010* can be used and requires a Windows MultiPoint Server 2010 CAL (WMS CAL) for each access device (and for the host computer if the host computer is used as a user station).** The diagram at right shows an example configuration with five users sharing a single computer running Windows MultiPoint Server 2010.

For further details on Microsoft’s multi-user licensing please refer to Microsoft’s website and licensing brief titled:

* Windows MultiPoint Server 2010 from Microsoft, and vSpace for the SPEED-09 for WMS from SPEED are both planned for the first calendar quarter of 2010

** Note that under Microsoft Volume Licensing Academic Programs, Windows MultiPoint Server 2010 Academic is required on the host computer and both a Windows Server CAL and WMS CAL are required for each user station.

*** SPEED supports Windows Server 2003 R2 and Windows Server 2008 today. Support for Windows Server 2008 R2 is planned in 2010.