As a wave of consolidation sweeps over companies, branch offices are stripped of servers and everything is moved to the data center. Even file servers are now being consolidated into large networked storage infrastructures and removed from the branch offices. So all that is left in the branch office are the desktops, right? Not so fast!

Many companies are looking to reduce desktop administration costs. With IT staff becoming more centralized also, branch-office desktops become difficult to manage.

A few companies are taking this consolidation trend to its extremes: house the desktops in the data center and deliver applications to a thin client. This type of desktop consolidation is most often reserved for special cases - call centers and back-office processing centers where there are a large number of single-application tightly managed desktops.

We see four approaches to desktop consolidation:

* Application Sharing, with thin clients accessing a presentation server, most often Citrix or Windows Terminal Server. Here, the desktop runs a single, lightweight client application or just a browser plug-in. The applications run on servers in the data center and are shared among many users.

* Web-based applications. Where possible, companies may migrate the main application to a Web-based platform and deliver it over a WAN to a browser. The thin-client desktop is the browser itself, and the rest of the applications on the desktop are stripped down or removed.

* Desktop blades. Some vendors are offering blade desktops. Like blade servers, these are densely populated racks of single-circuit desktops. The desktop applications run on the blade and are delivered to users via an IP-based remote keyboard, screen and mouse (like a KVM).

* Virtual desktops. This approach grew out of the server virtualization space. Using a hypervisor from VMWare, Microsoft or Xensource, desktops are run as virtual machines within a physical server. Access to the desktop is via Remote Desktop Protocol or something similar. Multiple virtual desktops can run on a single server, thereby increasing utilization and flexibility.

While these thin-client desktops are used in limited circumstances, they offer tremendous flexibility in terms of IT operations and support. The market for desktop virtualization is still nascent, but clearly there is room for different technical approaches to this problem. One of the key advantages of the virtual desktop option is that it leverages a common skill set with server virtualization, and possibly the same set of hardware.