In the past, those who either needed or wanted to use Windows on Apple hardware had to resort to emulation software. Performance was sluggish at best, as the software sought to translate the instructions from Windows’ x86 code to and from the PowerPC chipset that then powered Apple hardware.

But since the introduction of the MacBook Pro in January, Apple has begun shifting its hardware away from PowerPC and onto Intel chips. Most remarkably of all, it released Boot Camp (August 2006, page 62), allowing you to natively reboot an Apple Mac into Windows, effectively making Apple hardware like any other PC. There is, however, another option that the switch to Intel has brought: virtualisation.

Unlike Boot Camp, which requires you to close down Windows entirely to boot into OS X (and vice versa), Parallels Desktop allows you to run Windows alongside OS X, so that switching between operating systems is as simple as switching from Word to iTunes.

And we mean literally alongside too if you choose. While you can constrain the guest operating system to a floating window, you can also choose to have Windows run full-screen. On a system that supports two displays, you can have Windows running on one screen and Mac OS X on the other. Best of all, because Windows functions as just another OS X window, you can simply sweep your mouse from the side of one screen and onto the other.

This has another advantage over Boot Camp: you can use all the refinements
to trackpad control that Apple has added with new laptops. Its insistence on
a one-button trackpad is frustrating, but now you can at least perform a right-click by holding down two fingers on the trackpad surface while clicking.

Parallels is simple to set up too; a wizard walks you through the process of creating a virtual machine before prompting you to install your own copy of Windows, or you can start with a blank configuration and set things up to suit. This configuration information is held in a single file, while the virtual hard disk is held in another. Restoring Windows to an earlier state involves nothing more complicated than copying an older hard disk document over the current one.

An included utility can resize hard disk documents (upwards only), but Windows doesn’t recognise the additional space until it’s formatted and, since there’s no native way to re-partition on the fly within Windows, the easiest method is to set the correct size to begin with. The versions of Parallels for Windows and Linux (which, sadly, don’t support OS X) boast the ability to create virtual floppy disk images, lacking in the Mac edition. No big deal if you just want to install XP, but most earlier versions of Windows do require boot floppies.

In use, it’s all snappy and simple. Networking simply piggy-backs onto the Mac’s connection and, while dragging files directly between guest and host operating systems’ desktops isn’t supported, it’s easy to set up shared folders.

Idling, Parallels running Windows XP took around 16 percent of available CPU power on our 2GHz Core Duo-powered MacBook. Windows starts quickly too – under 10 seconds for a fresh install. It can also be ‘suspended’, so you can be back working in Windows and any open applications in seconds.

Running our real-world application benchmarks under Parallels, and then natively under the latest beta version of Boot Camp, virtualisation performed surprisingly well – the overall score of 0.65 is that of a respectable notebook. Our punishing multi-application test ran at 45 percent that of native (the speed the notebook ran at under Boot Camp), Office tasks at 57 percent of native speed and Photoshop at 65 percent of native speed. This was with Parallels’ RAM allocation set to the maximum 1.5GB recommended by the application, while native performance had all 2GB. The Parallels hard disk document was also on a Mac partition with lots of other data, while Boot Camp creates a clean partition on the hard disk. Ultimately, this isn’t going to be a panacea for performance-critical applications, but for light-to-medium office use the performance is more than adequate.

There are a few other downsides: support for USB can be erratic and is limited to USB 1.1 speeds; the documentation and interface could use sprucing up; and present Vista builds aren’t supported. Nevertheless, Parallels is by far the most convenient way to run Windows alongside Mac OS X we’ve seen.