My MacBook Pro has a split personality because it runs Mac OS X 10.4.7 and Windows XP Pro!

When Apple released the first Boot Camp Public Beta version, which installed Windows XP on Intel-based Macs, I tried it right away. That allowed me to boot my MacBook Pro into Mac OS X or Windows XP Pro, but not both at the same time.

I soon got tired of having to reboot each time I wanted to switch between Windows and the Mac. Parallels Desktop for Mac (PDM) solved that problem!

PDM is an x86 CPU emulator, similar to Microsoft's Virtual PC (which was recently discontinued), but much more powerful. Unlike Virtual PC, PDM supports many operating systems, not just Windows XP. PDM can run several Linux flavors and other versions of Windows. If you have enough disk space, you can run several operating systems on your Mac at the same time, without rebooting. For tech heads, this is a wonderful feature!

Installing PDM was easy. PDM can be downloaded from www.parallels.com. In addition to PDM, you also need a license to run whatever operating system(s) you plan to use. Parallels does not come with any operating systems.

The Quick Start Guide provides clear installation directions. Installing PDM and Windows XP Pro was easier than installing Windows XP with Boot Camp; Parallels does not require you to burn a driver CD.

The default hard drive size that PDM uses for a virtual computer is a bit small for my taste. Since PDM creates a virtual disk (which is stored as a huge file), the size of that disk can be changed by using a utility called ImageTool that comes with PDM. Unfortunately, Windows will not use the additional disk space; you need to use a disk partition utility to mount the added disk space as a separate partition.

Once you set up a virtual machine for PDM, you can run Windows XP in that virtual machine. Because PDM treats operating systems as applications, Windows XP can use most of the hardware that is available to Mac OS X. Each virtual machine runs in a separate window.

Although PDM is not suitable for games and other applications where processor speed is important, it works well for many applications. In fact, I installed the personal version of Oracle (a powerful database) on my Windows XP virtual machine and loaded a database with 135,000 records and it works fine.

When I installed Windows XP Pro under Boot Camp, I had to configure it to use my wireless network. With PDM, Windows XP Pro used the wireless connection without any need to configure it. Quite unexpected. I also get the full functionality of my MacBook Pro's trackpad from within Windows XP. To do a Windows right-click, hold down the alt and shift keys while clicking.

For those who have Bluetooth devices, please be aware Bluetooth does not work under PDM. The trackpad's double-finger scrolling feature and the energy server do not work with Boot Camp, but they do with PDM. Regardless of how you run Windows XP on an Intel-based Mac, I suggest you use a mouse with a scroll wheel and two buttons. A Mighty Mouse will not be too useful either for multi-button functionality because the buttons do not work well with Windows.

With PDM, you can only mount one USB disk drive at a time. I tried to connect two USB jump drives under Windows XP. The first drive I plugged into my USB 2 hub was seen by Windows. The second jump drive only showed up on the Mac OS X desktop.

PDM allows only one network interface at a time; you cannot use Airport and a wired network card simultaneously Boot Camp does not have that restriction.

When you click on the window for a virtual PC, the operating system that's running there controls the Mac's keyboard and mouse. To return control to Mac OS X, tap the control and option keys at the same time. To return keyboard/mouse control to the virtual PC, click on its window. This works well, but it takes a bit of getting used to.

The big question is, why spend $80 for PDM in order to run Windows XP on an Intel-based Mac rather than use Apple's free Boot Camp Public Beta to install a native boot version of Windows XP? Boot Camp is the best choice for those who need to run Windows XP at its maximum speed. Users of audio and/or video software fit into that category. Parallels is best for people like me who need to run Windows software, but speed is not that important. PDM is the also best choice for those want to run an operating system other than Windows XP.

In summary, PDM is the choice for those who want simultaneous OSs or non WIN XP, and for whom speed is not an issue. In either case, keep in mind you will also need a legal version of WIN XP.