Where Parallels beats VMware Parallels Desktop 5 and VMware Fusion 3 both have new support for DirectX 9.0c Shader Model 3, OpenGL 2.1, and the Windows WDDM driver. These graphic hardware acceleration technologies enable support for Aero in Windows 7 and Vista, as well as 3-D gaming. Parallels Desktop 5 goes one step further and supports OpenGL 2.1 in Linux guest operating systems, enabling the Compiz interface to run in a virtual machine.
Despite similar graphics specs in Windows, Parallels is a little faster and can be more responsive. The differences are most noticeable when running Windows 7 Aero. VMware Fusion took 33 percent longer to start Windows and four times longer to restore a saved state from a suspended state. Parallels Desktop is also faster when switching to full-screen mode and when launching Windows applications, particularly when in a mode that hides the Windows desktop. This was on a 2.8GHz MacBook Pro with 4GB of RAM.
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.