You do not need a Microsoft license for this
Basic Windows Server – Remote Desktop from XP to Server 2003 – Part 11
When multiple people on a network need to access a Windows computer, you normally need a server version of Windows (for example, 2003) running Terminal Services.
However, you must purchase licenses from Microsoft to do this. If you only want to give one person at a time remote access to a computer, you can do this in Windows without Terminal Services, in both Windows XP and Windows Server 2003.
Right-click on My Computer in the Start menu and select the Properties option from the pop-up menu.
