Desktop virtualization is a similar approach to using terminal services, except that you provide a desktop virtual machine which you access through a suitable client (VMware's, or another solution like VNC).

You get centralized management of your desktops, because the desktops are located on your virtual desktop server, and you can closely control the resources allocated to each machine.

There are also security aspects; have a problem with the machine? Re-image it from a backup of the desktop that you made that you know was safe. Viri and trojan houses can be kept under control by using a virtual hard disk that can be deleted or re-generated. You can even use the technology in VMware that rolls back changes to the disk when the virtual machine is shutdown, returning it to the state it was when booted.