Overview

VDI - Virtual Desktop - is handled by Citrix using XenServer and XenDesktop 2.0 technologies. Trial/Express versions of both are available, as very well described (May 20th 2008) here.

The site above provides far better information than can be replicated here, but as a reminder only, ZenServer functions in a similar manner to VMware ESX (both bare metal installations) and Xen Desktop provides access to virtual PCs (XP/Vista).

XenDesktop, additionally, can access VMs stored on either XenServer or VMware ESX and versions range from the (free) Express version to Enterprise verions.

How does on access a VM in Citrix? Citrix uses a broker service which handles authentication (to Active Directory) and then directs the user to their VM. This broker service runs atop Windows Server 2003 and is called the DDC (Desktop Deliver Controller).