With the upcoming release of Microsoft Windows 7 many enterprises are re-evaluating the state of their legacy desktop applications, both custom developed and purchased from third-parties, and are finding that migrating those applications to Windows 7 (or Windows Vista for that matter) may be expensive or otherwise impractical. This difficult situation has been one factor hampering the deployment of Windows Vista in the enterprise. As a result, Microsoft has created several technologies to allow enterprises to deploy XP applications in a virtual desktop environment running under Windows 7. This approach will allow an organization to make use of older XP applications while taking advantage of the other solid enterprise features that will be available under Windows 7. With respect to application virtualization, you may have heard about the new "XP mode" form of virtualization that will be available within Windows 7, but the complete picture of Microsoft's application virtualization strategy is much bigger than this one feature, in fact so broad and wide ranging that it can be very confusing to navigate the different technologies and acronyms. I know that I have a difficult time keeping things straight. This posting will be an attempt to clarify the different pieces of the puzzle. To start let's review the different application virtualization technologies available from Microsoft:

• Windows 7 XP Mode – This is the ultimate integration of Virtual PC like functionality within the host OS. And the integration combines Virtual PC with a ready to run guest OS version of Windows XP built into a Windows 7 host OS. The integration extends further though so that applications are isolated from the host OS by running within the virtual XP environment, but are at the same time are integrated with the host OS user interface to an extent that the XP applications appear in the launch Start Menu and running task bar. This feature will be available for Windows 7 Professional, Windows 7 Ultimate and Windows 7 Enterprise customers, but will not be available out-of-the-box when Windows 7 is released. End users will be able / required to deploy and maintain the details of the XP environment and XP applications on their own. Also, be aware that this feature requires Intel™ Virtualization Technology or AMD-V® at the CPU level and for these features to be enabled at the PC BIOS level on the desktop.
• Microsoft Enterprise Desktop Virtualization (MED-V) – This technology is a compliment to Windows 7 XP mode in that it adds enterprise application management to allow for centralized deployment, configuration and management of XP applications. This framework allows IT to create and deploy virtual PC images, provision those images and apply user policies for using those images on any managed PC. MED-V v1 functionality is available now for enterprises to allow the use of XP applications running under Windows Vista and gives enterprise Vista users "XP mode" like functionality. Later MED-V v2 functionality will add support for Windows 7.
• Microsoft Application Virtualization (APP-V) – While it would appear to be related to the above two technologies, APP-V is in fact quite a different product. This technology, through a combination of server side and client side components, allows for any enterprise application to be deployed to desktops in a just-in-time manner, whereby the application is "sequenced" for deployment using the System Center Application Virtualization Management Server and streamed to clients in an isolated and centrally configured manner. This approach allows for applications to be deployed in a centralized manner while at the same time minimizing the impact on the client host operating system. This product, which is currently available for enterprises, also assists in resolving application to application compatibility issues.
• Microsoft Desktop Optimization Pack (MDOP) – This group of tools is available to enterprises under Software Assurance licensing, is comprised of six individual components that assist in managing applications which run under Microsoft desktop clients in an enterprise environment. These components compliment rather than replace the existing Microsoft based management tools with which enterprise IT is already familiar. Both MED-V and APP-V are two of the available technologies that are available under the umbrella of MDOP. Any enterprise interested in client based application virtualization and who is under SA licensing should evaluate and understand this group of tools.

With the profusion of options for application virtualization, how does one make sense out of the confusion? Here are some suggestions for running XP Line of Business Applications on newer versions of Windows (Vista and/or Windows 7):

1. For smaller organizations who do not yet have a centralized client management strategy or who are not currently under SA licensing, you will be forced to wait for Windows 7 to be released and at some time later for the XP Mode functionality to be released. This will allow end users the ability to install and run XP Applications on Windows 7 client workstations.
2. For larger organizations, that have a current or future need to run XP Applications on newer Windows clients, it makes sense to evaluate Microsoft Enterprise Desktop Virtualization under the MDOP suite which will give you XP Mode like capabilities under Windows Vista in a centralized manner, even if you plan on waiting for Windows 7. Understanding this tool will greatly assist in having a successful deployment strategy.
3. For larger organizations looking for a centralized approach for centralized deployment of all enterprise desktop applications should evaluate Microsoft Application Virtualization under the MDOP suite which assists in making desktop application deployment as low-touch as possible.

If it's as confusing for you as it is for me, it's hard to understand the different components of Microsoft's application virtualization technologies without a score card. I hope that this information has helped reduce your confusion.

Jim Kita