Desktop virtualization comprises of many different types of virtual desktops. One option is to use a Hosted Shared Desktop model, which consists of a published desktop running on a Citrix XenApp server.
One of the goals when creating a design for Hosted Shared Desktops is to try and maximize scalability while still providing an adequate use experience. Hosted Shared Desktops provide an advantage over other desktop virtualization techniques by only requiring the use of a single operating system, which significantly reduces user resource requirements and helps improve scalability numbers.
This planning guide provides resource allocation recommendations for users running on a Hosted Shared Desktop on either Windows Server 2003 or Windows Server 2008.