Although many think immediately of Hyper-V when the words "Microsoft" and "virtualization" appear together, the truth is that the software giant offers a variety of virtualization solutions that span the needs of nearly every possible customer segment. Virtualization comes with important cost savings and is a key component in the move towards hybrid- and fully cloud computing-based environments. But as Microsoft implicitly reminded us this past week, it's also a great tool for the PC desktop.

Microsoft offers three major desktop virtualization solutions and two of them--Windows Virtual PC/XP Mode and App-V--were just updated in important ways. (The third, Microsoft Enterprise Desktop Virtualization, or MED-V, previously code-named Kidaro, shipped in 1.0 form earlier this year.) Let's take a quick look at these updates.

Windows Virtual PC and Windows XP Mode
Both Windows Virtual PC (WVPC) and Windows XP Mode were recently made available in Release Candidate (RC) form, and Microsoft expects to ship the final versions of each by the time Windows 7 becomes generally available on October 22, 2009. Essentially an out-of-band update to Windows 7, WVPC is a desktop virtualization solution that integrates a bit more deeply with the OS than did previous Virtual PC versions. It (finally) provides support for USB devices in guest environments, can "publish" virtualized Windows XP, Vista, and 7 applications directly to the host Windows 7 desktop for a more seamless experience, and can share folders, clipboards, and printers between the host and guest environment.

Microsoft has been pushing a special WVPC add-on called XP Mode as well, and for good reason: XP Mode is a specially preconfigured virtual XP with SP3 environment that, when installed, provides all of the seamless host-to-guest/guest-to-host features mentioned above. But the kicker here is that XP Mode includes a fully licensed and free version of Windows XP: As long as you have Windows 7 Professional, Enterprise, or Ultimate, you get XP Mode for free. It's a perk of the new OS.

In case it's not obvious, XP Mode isn’t required for most XP applications. Instead, most XP applications will simply run natively under Windows 7. XP Mode is designed for those legacy or custom applications that won't, for whatever reason, run natively under Windows 7. In many ways, it's a last resort option that simply provides that final measure of compatibility.

WVPC is a powerful solution for individuals and small businesses, but it's lacking in one crucial area: It's not managed in any way and comes with no central administration capabilities, so it's unsuitable for larger businesses and enterprises. No problem, as that's where MED-V comes in. MED-V is basically the managed, centrally administered alternative to WVPC with policy-based control, and it offers the same basic functionality as its unmanaged cousin.

App-V 4.6
Like MED-V, Microsoft's Application Virtualization (App-V) solution is delivered as part of the Microsoft Desktop Optimization Pack (MDOP), which is available to Software Assurance (SA) volume license customers. App-V (previously Softgrid) takes a different approach to virtualization than MED-V, however. With App-V, applications are packaged on the server and streamed to desktops when needed. These virtual packages are completely sandboxed from each other and from the host environment, preventing the so-called "DLL hell" compatibility issues that have bedeviled many an IT administrator, especially in mixed environments.

The latest version of App-V, App-V 4.6, is now available in beta form. This release adds support for x64 (64-bit) environments. (Previously, App-V supported only 32-bit x86 environments.) It also provides compatibility with both Windows 7 and Windows Server 2008 R2. Microsoft says the final version is expected in the first half of 2010.

Windows 7 Schedule Reminder
Finally, I'd like to highlight some of the Windows 7 releases that have occurred in the past week. Microsoft is issuing its new OS with a "rolling thunder" release schedule during which time different customers will be able to get Windows 7 at different times. As of today, MSDN and TechNet subscribers can download Windows 7 RTM in English. And volume license customers with an existing Software Assurance license can download Windows 7 RTM in English via the Volume License Service Center (VLSC).

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