Take the Free Way to Virtualization

By Joseph Moran | Posted August 28, 2007

Using virtualization to run multiple operating systems on a single physical computer was once mainly the domain of ubergeeks and IT administrators, but these days small businesses are showing interest in the technology, whether it's to kick the tires on a new operating systems, or just to continue using an application designed for a now obsolete operating system.


Microsoft Virtual PC 2007
Virtual PC 2007 in action.
Virtualization's increase in popularity is in part due to Microsoft's decision several years ago to offer its Virtual PC 2004 software (which it acquired from now-defunct Connectix) for free. Some users soon found that there was a catch, however, because VPC 2004 didn't work particularly well with Windows Vista, whether as the guest (virtualized) operating system or as the host OS running natively on the system.

With the new Virtual PC 2007, Vista-related issues are no more (at least technical ones — more on that in a moment). While VPC 2007 doesn't address all of VPC 2004's limitations — nor for that matter does it offer the same level of features as virtualization products like Parallels Workstation or VMWare Workstation —it does handle the basics well. And like its predecessor, VPC 2007 is available free of charge, which for many will be reason enough to try it.

Licensing Issues
Before you consider using VPC 2007, it's important to be aware of Microsoft's fairly restrictive licensing requirements for the software. For starters, VPC 2007 is licensed onlyto run on the following versions of Windows — Vista Business, Enterprise, or Ultimate Edition; Windows Server 2003; and Windows XP Professional and Tablet Editions.

You may notice that Windows XP Home and Windows Vista's Home Editions (Basic and Premium) are conspicuously absent from this list. If you try to use VPC 2007 on any of those, the install routine will admonish you with a warning dialog, but surprisingly, you can click away the warning and proceed with the installation anyway. (Actually, it's not that much of a surprise, considering VPC 2004 does the same thing when installed on XP Home). To tie your hands even further, Microsoft explicitly forbids the use of both Vista Home Basic and Premium within any virtual environment, not just with Virtual PC 2007.

There has been a fair amount of angst about Microsoft's decision to restrict the use of both VPC 2007 and Vista for what are believed to be marketing rather than technical reasons. Microsoft's policy may yet change — the company has reportedly come close to amending it at least once already — but for now, you should be mindful of the various license restrictions that come with the software.

Setup and Virtual Machine Configuration
After downloading and installing Virtual PC 2007, the software makes setting up virtual machines for guest operating systems simple. You pick the operating system you want to install from a list provided by a VM wizard, and VPC 2007 then configures your VM to use an appropriate amount of memory and disk space.

This being a Microsoft product, the guest OS menu consists primarily of other Microsoft products (Windows 98 through Vista for client operating systems, plus NT/2000/2003 Server), but since the choices merely reflect minimum RAM/disk amounts, you're not necessarily limited to installing the OS specified.

Initial values for either RAM or disk space can be adjusted later in the wizard, or even after a VM has had an OS installed. When it comes to disk space, VPC 2007 uses dynamically sized virtual disks (.VHD files), in which the amount of space indicated (anywhere from 8 - 64 GB) actually represents the maximum the disk can set aside. This helps conserve space by allowing dynamic virtual disks to start out small and consume additional space only as needed.

To set up a guest operating system, you can use a newly created virtual machine to capture the DVD drive containing the OS disc, or else mount an ISO image of the disc (in either case, you must have a licensed and unused copy of the operating system). We installed multiple versions of Windows (XP Home and Professional, plus Vista Ultimate) plus SuSE Linux 10 without any problems. Although it worked fine with Parallels Workstation, graphics and mouse recognition problems prevented us from successfully installing Ubuntu 7.04.

By the way, if you already have VPC 2004 (with Service Pack 1) installed on your system, VPC 2007 can install on top of it and will identify and work with any virtual machines you already have. When we performed an upgrade from VPC 2004, all existing virtual machines (a half-dozen) were recognized and ran without a hitch.

The number of virtual operating systems you can run at the same time with VPC 2007 mostly depends on how much system memory you have and how you choose to allocate the memory among your host's various guest operating systems. If you want to run several guests concurrently without noticeably impacting the performance of the host, 2 GB of RAM and a reasonably fast CPU is a good place to start. We were able to simultaneously run two guest operating systems comfortably on our Athlon 64 X2 4400+ system with 2 GB of RAM.


Microsoft Virtual PC 2007
The Virtual PC 2007 console.

VPC 2007 can provide improved performance by utilizing the hardware virtualization support built into many recent AMD and Intel CPUs, but because our system's older processor lacked such support, we couldn't take advantage of this hardware-assisted virtualization. Having a dual-core CPU is of limited value since VPC 2007 can only make use of a single CPU.

To switch keyboard and mouse control between guest and host operating systems, VPC 2007 utilizes a customizable hotkey, but if you're using a supported operating system (the ones mentioned above, or OS/2), you can also install Virtual Machine Additions (VMA). VMA provides additional features and tighter integration between host and guest(s), including the ability to move seamlessly between guests (or guests and the host) sans hotkeys, plus support for folder and clipboard sharing and dynamic resizing of VM windows.

Like its competitors, VPC 2007 allows you to suspend and resume guest OSes and provide them with various levels of network connectivity by automatically bridging the host PC's network adapter. Unfortunately VPC 2007 doesn't offer USB interface support, and while not everyone will miss it, it is often useful to be able to recognize USB devices (particularly flash or hard disk drives) within virtual machines.

Feature and licensing limitations aside, Virtual PC 2007 will be a good choice for many especially when compared to the cost of other options (Parallels costs $50 and VMWare Workstation is $190). Perhaps not surprisingly, Microsoft is pushing VPC 2007 as a platform for evaluating other products in the company's repertoire; you can download a variety of ready-made VHD files at www.microsoft.com/technet/try/vhd/default.mspx.

Pros: Free; provides a simple way to use an older application or operating system

Cons: Not licensed for use with XP Home, Vista Basic or Premium; no USB support; incompatible with Ubuntu 7.04

Article appeared originally on WinPlanet.com.

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