What to expect from Windows 7

Part 6

Windows Virtual PC and XP Mode

XP mode is one of the few surprises to emerge from the Windows 7 development process. Unveiled less than two weeks ago, it’s received a disproportionate share of news coverage. Will it turn out to be a killer feature or just an esoteric add-on? It’s still too early to say.

Windows 7 includes compatibility tools similar to those found in Windows Vista, which allow you to work around minor compatibility issues so that you can install and run an application that was written for an earlier Windows version. XP Mode is for more chronic problems, where a program that runs fine in Windows XP simply won’t work on Windows 7. It uses a spiffy new version of Microsoft’s venerable Virtual PC program to run a fully licensed copy of Windows XP SP3 in a virtual machine. (XP Mode is available only with Professional, Ultimate, and Enterprise editions of Windows 7 and requires hardware virtualization support in the CPU.) I found the setup reasonably straightforward. First you run a small update package to enable Windows Virtual PC, and then you install the Virtual Windows XP package to unpack the XP virtual machine and set it up.

The most popular use for XP Mode is to run a critical business program that won’t run otherwise, such as a point-of-sale application or an accounting package. Looking around my office, I found a perfect test case as well. My primary PC runs Windows 7 x64; I have a USB scanner that doesn’t have x64 drivers but has a perfectly functional set of XP drivers. It also comes with a fully licensed copy of Adobe Acrobat 7.0, which has compatibility issues with Windows 7.

The new Windows Virtual PC includes the capability to attach USB devices. I plugged in the scanner to a USB port on the host machine, attached the device to the XP virtual machine, and proceeded to install Acrobat and the XP scanner driver without issue. I then had no trouble scanning a handful of documents.

All the code that makes XP Mode possible, including Windows Virtual PC, is still in beta form, so it’s difficult to evaluate the software fairly. Although it works, it wasn’t as seamless as advertised and occasionally confused me with its behavior. In my case, I couldn’t use the so-called seamless mode to initiate a scan. I had to load the full XP virtual machine, attach the USB scanner, and then click the scan button each time.

The new Virtual PC program is impressively lightweight, using about 280 MB of RAM to host a 256MB virtual machine. I found that keeping the XP virtual machine running when hibernating took a toll on wake-up times. The program had a fair number of glitches, too. For example, I couldn’t create or edit a virtual machine when logged in using a standard user account. Each virtual machine is tied to a specific user account, so you can’t share an XP program between two accounts using a VM in a common location. And the process of switching between Virtual PC and seamless mode was cumbersome, with some truly inscrutable error messages.

In the gallery: XP’s seamless mode, the Virtual PC interface, and examples of confusing error messages

Source: http://blogs.zdnet.com