Is 'XP Mode' in Windows 7 something you'd want to use?

Since Microsoft's acquisition of SoftGrid application virtualization two years ago, the company's engineers have known that this technology could present an attractive and even preferable shortcut to the perennial problem of downward compatibility. If you set aside the problem of affordability for a moment, the other key reason businesses remain hesitant to adopt Windows Vista at present is because of the uncertainty that existing business applications will be seamlessly portable into the new environment.

This is much more of a problem for businesses than consumers, although a lot of the excitement around what Microsoft's calling "XP mode" in Windows 7 (whose first and probably only Release Candidate should be available to the general public tomorrow) came from everyday users who perceived the company's move as a nod toward the efficiencies of the past, as opposed to the planned obsolescence of the future. The fact is, businesses continue to invest in software up front with the expectation that it will pay off in the long term, depreciating it like an asset rather than supporting and nurturing it like a resource. And it is for those businesses that Microsoft must ensure that it facilitates and ensures the same general infrastructure over time.

So would everyday consumers have reason to use Windows 7's new Windows Virtual PC in XP Mode? Not typically. Consumer-grade software is usually updated with the moving target of Windows evolution in mind. But if those consumers are also businesspeople, and they're faced with a situation where they need to be able to run their office's software that was developed in the era before .NET, where resources were either built-in or dependent upon DLLs or OCX's (the version of DLLs originally built for Visual Basic) then Windows 7 gives those consumers a serious alternative to having to buy or use two computers. There are indeed many home office workers who have to maintain "the XP machine" separately, and who either cannot or aren't permitted to update those machines for fear of rendering obsolete the software upon which they depend.

Essentially giving away a working XP kernel -- which is what Microsoft has decided to do -- is the company's boldest move toward neutralizing the negative impact of the downward compatibility argument on the operating system. The press materials last week presented by Microsoft did not explicitly specify that both Windows Virtual PC and the XP Mode drop-in (a pre-installed virtual machine) would be free, so even though a Microsoft FAQ for the general public stated they would be, we weren't certain we should report that without direct confirmation. (We'd been burned on that count before, and with a virtualization-related product.)

Over the weekend, Microsoft spokespersons rallied to confirm the licensing situation. Users of Windows 7 Professional, Enterprise, and Ultimate SKUs, a spokesperson confirmed to Betanews Sunday afternoon, will not be charged extra to download either Windows Virtual PC or the XP Mode drop-in. But the downloads will be available "for all customers," the spokesperson added, leaving open the possibility of future fee-based licensing for users of other Win7 SKUs. For now, as is the case with Vista, the Ultimate SKU is the only consumer-grade edition of Win7 that enables the business-class features of the operating system, which also include such things as group policy management.

In a marketing effort clearly intended to contrast its Vista push for bigger, bulkier PCs, Microsoft has been diligent this time around in presenting Windows 7 as not requiring more hardware or horsepower than Vista. Last week, the company made certain Mary Jo Foley knew right away that at least the 32-bit version's specification profile was essentially the same for Win7 as for Vista.

But you'd expect XP Mode to require something extra from the hardware, and here is where the company's playing things low-key. Windows Virtual PC requires a computer with 2 GB of DRAM and 20 GB of free storage space for the creation of a virtual hard disk. The XP Mode drop-in consumes 2 GB on its own, plus another 15 GB for virtual storage. Experience with WVPC's predecessor, Virtual PC 2007, tells me you really need 4 GB of DRAM at least, and 50 GB of total free space. On the one hand, that's probably too much for your "old PC," but you don't want to run Windows 7 on an old PC anyway -- not so it can run Windows XP on the side. The users who will take advantage of XP Mode will be those who require the convenience and efficiency of having both modes of operation in a single machine.

The other big requirement -- one which Virtual PC 2007 did not have -- was for hardware-based virtualization support through the CPU. If you're judging from CPU model numbers alone, you could get confused by this; but typical consumers don't make such judgments based on model numbers anyway. They look for logos such as the Intel vPro and AMD-V symbols, which certify a machine as supporting virtualization in hardware.

For AMD-based machines, practically all Opteron server CPUs support AMD-V, as do all Phenom desktop processors, all Athlon 64 X2 processors with Socket AM2 dating back to 2007, and all dual-core Turion 64 X2 processors. For Intel desktop CPUs, all dual-core Core 2 Duo E6xxx (65 nm), E7xxx, and E8xxx series, as well as Extreme branded CPUs support Intel VT, and all Core 2 Quads including Extreme support it as well. In mobile, the picture is a little spottier: Only some of the first mobile Core 2 Duo T5xxx series support VT; but in the 45 nm generation, all of the Core 2 Duo U-series, the T9xxx, the P, SP, SL, and SU series support VT. All Extreme branded mobile CPUs support VT, as well as all mobile Core 2 Quads.