InfoWorld review: Windows on the Mac
Parallels Desktop 5 and VMware Fusion 3 get faster, smarter, and optimized for Windows 7, while Sun’s VirtualBox 3.1 lags behind
The CPU utilization, as measured by Activity Monitor, was typically lower with Parallels when Windows 7 Aero was running. When starting Windows 7 in VMware Fusion, CPU utilization reached above 150 percent, which temporarily stopped the Mac when other Mac applications were open. When starting Windows 7 in Parallels Desktop, CPU utilization spiked for a second to 130 percent, but mostly stayed below 50 percent.
The most hardware-intensive mode is one that hides the Windows desktop and taskbar, and displays only the windows running applications and Windows Explorer. Parallels has two such modes: Coherence and the new Crystal. VMware calls its integrated mode Unity. All three virtualization products can also run a guest operating system in its own window or in full-screen mode.
Because the Windows taskbar is hidden in Coherence and Unity modes, Parallels and VMware will minimize free-floating Windows windows to the Dock, just like Mac apps. Open Windows applications get their own Dock icons as well. Both virtualization programs will also place Windows apps in the Mac's Application Switcher (Command-Tab or four-finger horizontal swipe on trackpads) and display Windows application windows in Mac OS X's Expose.
Parallels Desktop goes a little further with this Mac integration, applying these features when the Windows desktop is displayed (single-window mode). Fusion supports Dock icons for Windows apps only in Unity mode.
Parallels is also more Mac-like in enabling you to launch Windows applications from Mac OS X, even when Parallels isn't running. It puts a Windows application folder in the Dock, just as Snow Leopard has a folder for Mac apps. Add a second Windows virtual machine, and a second folder is tacked on. Fusion appends a Start menu to the right side of the Mac's top-screen menu bar. It works, but I prefer the more standard Dock approach.
Additionally, when a virtual machine is running in Coherence mode, the Parallels Dock icon doubles as a Windows start menu. If you can't keep track of which mode supports what, a screen appears when you switch modes, telling you where you can find these items. (The new Crystal mode is a minimalist version of Coherence. It hides the Parallels Desktop menu and Dock icon, leaving only a small Parallels icon in the Mac menu bar at the top of the screen.)
Another nice touch: When you switch between modes, a transparent dialog appears, telling you what mode you're entering and showing you where you'll find various interface elements. One of my favorite Parallels features is complete support of track pad and Magic Mouse gestures in Windows applications. For instance, the multifinger horizontal swipe works in Internet Explorer to go forward or backward.
When in Coherence mode, the Parallels Desktop Dock icon becomes the Windows Start button. That disappears in Crystal mode, replaced with a Start menu at the top.
Where VMware beats Parallels
That said, VMware Fusion 3 is a solid virtualization environment that some people may prefer. For instance, I had better experience playing Web-based video in Internet Explorer with VMware Fusion than with Parallels Desktop. VMware was able to play streaming video at Microsoft.com without adjusting anything. Parallels played only downloaded videos.
VMware Fusion 3 also has some useful interface features not found in Parallels Desktop. In full-screen mode, Fusion presents a small bar when you mouse over the center of the top edge of the screen. This bar presents options that let you do anything Fusion allows, including switch to single-window or Unity mode, suspend the virtual machine, take a snapshot, and a number of other tasks. In Parallels Desktop, you have only one choice when in full-screen mode: to exit the mode into single-screen mode.