Virtualizing the desktop represents an even larger opportunity than virtualizing servers, but it may take someone other than a brainy, high-level virtualization company to capitalize on it.

Did you assume I was referring to VMware? Well, you might be right.

Virtualizing desktops is fundamentally different from server virtualization. With the latter, data center cost savings and ease of management are paramount. With desktop virtualization, the same savings materialize. But before you can realize the savings, you have to do things in a way that both pleases and serves the interest of users, and that's a different kettle of fish from advanced computer science.

VMware is on track to become a $1 billion company later this year, mainly on the strength of server virtualization in the enterprise. It also offers ACE as a means of virtualizing desktops. There's nothing wrong with ACE, a product set that sends virtual desktops down the wire from a central server and runs them in VMware Workstation on individual PCs or laptops.

But there's about a dozen ways of doing desktop virtualization and I'm not convinced VMware is the master of this space. Also, the price per unit is going to have to come down and will count more heavily on this side of the virtualization divide than on the server side.

For example, XDS capitalizes on interest in desktop virtualization by charging $39.95 a month per user to virtualize the display of virtual machines running on central servers and deliver that display to the user.

This is similar to what Citrix' Presentation Server does for Windows applications, delivering a virtualized display off a centralized server. But XDS capitalizes on Microsoft Virtual Server, VMware ESX Server or, better yet, free Xen running on the central server. XDS transports interactions between user and server and displays the results on a variety of user machines, including in a browser window or on simple thin clients, giving it a great flexibility in user devices. The enterprise sets up what virtual machines and applications it wants users to have. XDS delivers the results.

Another approach is taken by Alteris and AppStream, which teamed up to generate virtual machines on a central server, which they then stream with their applications down the wire to actually run on user desktops.

With either the VMware, Alteris, or XDS approach, an enterprise can decide that it wants to migrate selected users to Windows Vista but retain large groups of users on Windows XP. It can switch some users over to Open Office under Linux without sending technicians out to desktops and installing a new operating system and applications.

Virtualization brings options to the desktop that never existed before. One of them is that a user can run more than one operating system, but somehow I don't think the average Mac or Windows user is chomping at the bit to add Debian Linux.

Rather, the big gain comes in ease of setting up new users or wiping out the virtual desktops of former employees. Application sets can change easily; privileges can be upgraded or downgraded. Administration takes place primarily from a management interface in the data center. Administrators may never come face to face with the users they're managing, which may not be a good thing, but it's sure to save time, expense, and perhaps a few argumentative words.

And in the age of compliance, virtual user desktops can be partitioned into generally accessible vs. highly secure areas. A laptop got stolen? There's no way the thief is going to break into that customer list encrypted inside a password-safe virtual machine.

There are many more users awaiting virtualization than servers. Microsoft, VMware, or one of a dozen current start ups is going to hit it just right in this space, but so far no champion has emerged.