Booting Windows on the Mac

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The Basics

The first thing to understand is that there are two main ways to boot Windows on a Mac:

  • The first is by running Windows while in the Mac OS. This process is is known as virtualization and the two main products that allow you to run Windows virtualized are Parallels Desktop and VM Ware Fusion.
  • The second is by running Windows natively. This can be done through boot camp. Boot camp comes with all Macs running Leopard or higher.

Both of these methods will require the purchase of a FULL version of either Windows XP Service Pack 2, Windows Vista or Windows 7.

Virtualization Software


For almost as long as the Mac OS and Windows have co-existed there have been products to allow Mac users to run Windows within the Mac OS.

Today, the most widely used of these programs are VM Ware Fusion and Parallels Desktop. Although the two programs are more similar than not, there are some specific differences between the two. The specific differences are beyond the scope of this wiki but you can research them at the VM Ware Fusion Website and at the Parallels Desktop Website.

Characteristics of Virtualization Software

  • Windows will run inside of a window inside of Mac OS
  • Windows will run slower than it would run if it were running on its own - the speed of the Windows OS will be heavily dependent on the memory (RAM) inside the computer, with Windows Vista requiring more memory than Windows XP
  • Windows will be "stored" in a file on your Mac hard drive - because of the way that virtualization works, you will be able to move files between the Windows OS and Mac OS very easily
  • Almost all programs that work in Windows will work virtualized
  • Almost all hardware that works in Windows will work virtualized
  • Both VM Ware Fusion and Parallels Desktop will allow you to run windows from an installed boot camp partition (more on this below)

Benefits of Using Virtualization Over Boot Camp

  • The computer does not need to be restarted to run Windows as virtualization programs load Windows while still running Mac OS
  • File transfer between the windows and Mac OS is, for the most part, simpler
  • Virtualization can be combined with boot camp such that you can "pick and choose" which way you want Windows to run - either using virtualization software to run the boot camp partition or running the boot camp partition itself.
  • If a virus is caught in the Windows partition it will be almost impossible for it to affect the Mac OS - Note: while viruses that break this rule have been demonstrated in theory, they have never been seen in the wild

Downsides of Using Virtualization Over Boot Camp

  • There is a noticeable speed difference that can be minimized somewhat with a lot of memory (RAM) but can not be completely overcome
  • Windows games will be noticeably slower
  • Some (few) programs will not work in a virtualized environment

Requirements to Install Virtualization Software

  • Copy of virtualization software of choice (both VM Ware Fusion and Parallels Desktop have trial software than can be installed so that you can try both and decide which is better)
  • Copy of a FULL version of Windows XP or Windows Vista (more on this later)
  • Hard drive space necessary for windows installation
  • Significant amount of memory (RAM) - 1GB for Windows XP, 2 GB for Windows Vista recommended


  • If using time machine it should be set to NOT backup the Windows file created by Parallels Desktop or VM Ware Fusion. This is because the Windows partition is a large (over 1 GB minimum) single file that is changed regularly and every time it is changed time machine will re-save the ENTIRE file. This will lead to a slow backup process every hour that virtualization software is running and quickly diminished time machine hard drive space.

Frequently Asked Questions

  • Should I install Parallels Desktop or VM Ware Fusion?

Boot Camp


Apple's initial stance was that while they wouldn't support it, they would not prevent people from booting Windows on their Intel Macs [1]. Third party efforts to boot Windows on the Intel Mac were hampered by some architectual differences between the Intel Macs and current traditional Intel-based PCs (Intel Macs use EFI whereas traditional PCs use BIOS, among other differences discussed below). However, with the advent of boot camp Apple has now created a way that allow users to run Windows natively on Intel Macs very simply. Boot camp is now distributed on all Macs running OS 10.5 Leopard.

Understanding What Boot Camp Is

To understand what boot camp is, you must understand some key differences between Macs and PCs. In the past Macs and PCs had three major hardware differences: the CPU (Motorola for Mac and Intel/AMD for PC), the motherboard firmware (EFI for Mac and BIOS for PC), and the hard drive boot requirements (GPT for Mac and MBR for PC). With Apple's migration away from Motorola (supplier of G3/G4/G5 series and earlier CPUs) to Intel (Core Duo, Core 2 Duo) for their CPUs the CPU problem was fixed. The EFI of Macs can now emulate the BIOS of a PC allowing Windows to recognize the motherboard and internal components at the most fundamental level. Lastly, installing boot camp creates an MBR partition that allows Windows to boot from a Mac hard drive.

Boot camp consists of four main components:

  • Boot camp assistant: A program run in Mac OS that allows users to create a Windows partition on their hard drive
  • Boot camp preference pane: Allows users to change which is the default OS that the computer starts on boot up
  • Boot camp drivers: Enables Macintosh hardware to be recognized and used by Windows
  • Boot camp windows control applet: Allows users to change some limited settings of Mac hardware running within Windows.

Note: Boot camp does NOT include a copy of windows. To use boot camp the user must purchase a FULL version of either Windows XP Service Pack 2 (older versions will not run; however, there are ways to create an SP2 CD from older versions utilizing slip-streaming which is beyond the scope of this wiki) or Windows Vista. There is still debate as to whether it is legal to use OEM copies of Windows to install boot camp.

Because Windows is running natively (meaning, without the use of any other programs) using the computer hardware it is every bit as fast as using a Windows PC. In fact, some major hardware reviews have found running Windows using Boot Camp on a Mac to be faster than PCs running Windows when compared using standard benchmarking tests. This is a testament to the true speed of the native running of Windows.

When using boot camp the user should think of the boot camp partition as running Windows like they would be on a PC with similar hardware. In this fact, the Windows partition will be subject to the same threats as a regular Windows PC. Windows boot camp users can get viruses, spyware, and the like and protection is required in the same way that it is required on a PC.

Understanding Hard Drive Partitions and File Recognition

There are three major ways that hard drives are formatted in today's computers:

  • HFS+ - Format used by Macintosh OS X
  • FAT 32 - Format used by older versions of Windows (including Windows XP)
  • NTFS - Format used by Windows Vista and Windows XP

Each partition of a hard drive can be formatted in any of these three ways. Understanding the ways that the competing formats recognize and use files in the other partitions is an important concept to understand to create the best partition scheme for your uses.

HFS+ Partitions: HFS+ partitions can read and write files of FAT 32 partitions but can only read files of NTFS partitions. This means that if Windows boot camp is made into a FAT 32 partition the Mac OS will have full access to the files and it would act as a normal hard drive to the Mac OS. If the Windows boot camp partition is made into an NTFS partition the Mac OS will be able to read the files, but will not be able to write files to the partition. Note: there are 3rd-party programs that enable Mac OS to write files to NTFS partitions, but this is not a native property of Mac OS.

FAT 32 Partitions: FAT 32 partitions have a few limitations. First, the maximum size of a FAT 32 partition is 32GB. Second, the maximum size a file can be to be transferred from the partition is 4GB. You should NOT use FAT 32 if you need the Windows partition to be larger than 32GB. FAT 32 Partitions can neither read nor write HFS+ partitions. Using 3rd party software (the most common one being Macdrive) the Windows boot camp partition can both read and write the HFS+ (Mac OS) partition. FAT 32 partitions can both read and write NTFS partitions. Windows Vista cannot be installed on FAT 32 partitions

NTFS Partitions: NTFS partitions are required for installation of Windows Vista. NTFS partitions can neither read nor write HFS+ partitions but this feature can be enable with 3rd party software like Macdrive in the same way it is enable for FAT 32 partitions using Macdrive. NTFS partitions can both read and write FAT 32 partitions.

Benefits of Using Windows Boot Camp over Virtualization

  • Running Windows through boot camp is noticeably faster than running Windows through virtualization software - to this end, most recent games will require boot camp to be installed to run optimally
  • All Windows programs and hardware will run within boot camp without problem

Downsides of Using Windows Boot Camp over Virtualization

  • Viruses, spyware, and the like are a very real problem and while they cannot normally cross over to infect the Mac OS partition of the hard drive, if one has Macdrive (see above) installed, it is possible (albeit incredibly rare) to have a Windows virus infect the Macintosh hard drive
  • There are limitations to the manipulation of files between hard drive partitions as described above
  • To switch from Macintosh OS X to Windows using boot camp the computer must be restarted
  • To switch back to Macintosh OS X from Windows the computer must be restarted

Requirements to Install Virtualization Software

  • Copy of Mac OS X Leopard CD to install drivers in Windows
  • Copy of a FULL version of Windows XP Service Pack 2 or Windows Vista
  • Hard drive space necessary for windows installation

Frequently Asked Questions

  • Should I install Windows XP, Windows Vista, or Windows 7?

Running Both Virtualization and Boot Camp at the Same Time

Both Parallels Desktop and VM Ware Fusion allow you to boot the boot camp partition of Windows into the virtualization software engine within Mac OS. This has significant advantages:

  • It allows you to run Windows applications in Mac OS without having to restart the computer, but at the speed disadvantage of virtualization software - this is helpful for running basic programs like Microsoft Office 2007 or Quicken, etc., that do not require much processing power and would not see a noticeable performance difference running in the virtualized environment
  • It allows you to retain the option of restarting into Windows when the performance advantage is important - this is helpful for gaming and graphics applications that require significant processing power and would be slowed down if run virtualized

In these ways this is often seen as the "best of both worlds" option and is a frequently used combination.