Today, there are three principal methods to work with Windows or Linux on a Mac. You can run Windows natively from a dedicated disk partition with the help of Apple's Boot Camp, free with Mac OS X 10.5 Leopard; or use one of two commercial virtualisation programs. These allow an enclosed (‘virtual') system to be run within the main computer (‘host').
Parallels was the first to market with a solution for Macintosh, followed by long-term virtualization specialist VMware Fusion. Both are now mature products with excellent system integration to make it easier to run one or more additional operating system within OS X.
With the new Fusion 2.0, VMware has introduced several new features which further help the use of a client Windows virtual machine. VMware Fusion 2 now supports 64-bit operating systems, an increasingly important attribute in a multi-gigabyte RAM world.
The Snapshot function works like restore points function in Windows, allowing you to easily rollback any system changes in the event that malware or poor software is destabilising the virtual machine. VMware Fusion 2.0 now gives you multiple snapshots, and additional to this, Autoprotect provides a schedule for these snapshots.
Rather than have a complete OS desktop windowed on your screen, you can elect to work in Unity mode, so that just the foreign applications appear over the OS X desktop - complete with shadows behind windows and Exposé support. And with launch icons in the Mac dock, you can launch Windows or Linux apps without having to manually start the virtual machine first.
One reason why Mac users may be tempted to install Windows is to play PC games not ported to the Mac - but this has always been problematic for emulation and virtualisation solutions, as they couldn't directly access 3D acceleration in the graphics card. With Fusion 2 however, VMware has provided better compatibility, up to DirectX 9.0c with Shader Model 2. We tried a recent game, Tomb Raider Anniversary, and while the game could load it ran too slowly to be playable, with some image distortion. And sadly, the extra graphics performance does not stretch to giving Aero effects in Windows Vista as this requires Microsoft's WDDM and a whole new driver architecture.
Multiple processors are now fully supported, and with all new Macs having at least dual cores, these can now be usefully exploited for better performance. In use, even with one processor at work, we found a Windows interface in VMware Fusion 2 to be snappy and with good perceived speed of operation - even running Windows Vista. With both processors engaged, host CPU usage would often exceed 100% but there seemed less OS X slowdown than we noticed in earlier versions.
On our test computer, an Apple MacBook Pro 2.4GHz, we used a Boot Camp partition to test performance. Where the native speed from Windows Vista Ultimate 64-bit is 88 points from WorldBench 6 (with 4GB RAM), the virtual version measured 48, with 2GB of RAM assigned. When we switched to both of the machine's dual-core processors, this rose to a score of 55 points. In its defence, even though these figures are well below native speed, the Mac remained responsive at all times, suggesting VMware has done a good job of balancing CPU power between host and virtual machines.