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Windows 7 cleans up

Posted on 16 Jun 2009 at 00:00

While welcoming the arrival of a virtual windows xp in windows 7, Jon Honeyball still fears that Microsoft isn't being brave enough.

Well it turns out to be something like that, but as is always the case with Microsoft, it isn't the bold leap that we'd wished for. Nevertheless, it does open up some exciting possibilities. Essentially, Microsoft has raided its store cupboard and pulled out the box labelled Virtual PC, blown the dust off it, given it a makeover so that it looks more 2009 than 2004, and is preparing to drop the buffed-up result into Windows 7.

If you can remember that far back, Virtual PC was a software emulation of the Intel processor, what we had to make do with before proper hypervisors came along with their hardware-supported feature sets and high performance. What Microsoft has done is take the Virtual PC software and bundle it with a pre-cooked VHD (virtual hard disk) that contains Windows XP. This enables you to boot up Windows XP in a software emulation of an Intel processor and run it alongside Windows 7 - then, by some fiddling and behind the scenes rewiring, it makes sure that you can install old apps into this XP virtual machine rather than into Windows 7. The idea is dirty Windows XP apps will run better on XP, and any such dirty apps will be confined within the virtual machine.

To be clear, an XP application that won't run cleanly on Windows 7 is frankly a dirty, badly written embarrassment of a slug. But there's an appalling amount of this crap out there, often in quasi-mission-critical business applets without which the business will grind to a halt. To nail this problem, running the dirty applet in an XP VM is an obvious way of sorting out the problem and reassuring corporate IT departments hooked on such malware that it's alright to upgrade to Windows 7.

There are some questions about how the XP virtual machine will be portrayed onscreen - do you want a whole XP desktop within a window on the desktop of Windows 7? Of course you don't, so Microsoft has pinched a feature used by other desktop Hyper-V solutions to allow virtualised XP applications to sit directly on the Windows 7 desktop. All of which seems very good: XP apps run in real XP if you need that; Windows 7's compatibility score improves and everyone's happy.

Except for a few little niggles. First, this is only a very small step on the way to properly containerised versions of Windows, and because it's a software Virtual PC implementation it could be argued that it's a short-term measure only - is there really a future for non-Hyper-V solutions? Worse, it's going to be offered for only the business versions of Windows 7. I can't see the logic there from a packaging point of view, unless there's a big gotcha attached to the system that would threaten to upset home users - for example, it might be that configuring the XP VHD is a system administrator job, and if your users screw it up, blow it away and send them a new package. That wouldn't work so well in a world where users insist on being able to perform open-heart surgery on their own operating system...

And finally, there's no really deep documentation as yet about how all of this is going to be managed. Will that real XP installation count as a second licence, and if not, how is this to be policed? How do I install rolling patches and updates into the VHD on a weekly basis? Do I patch one and then redeploy to all machines, or can I patch live into the VHDs alongside the patching for Windows 7? Will I really get an XP licence, or is this one of those efforts where a software utility performs a migration from an existing installation into a new VHD? Much is left unanswered, but the prospect is still pretty enticing - even if it's only a tentative first step toward Microsoft using virtualisation on the mainstream desktop operating platform.

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