Which Macs can run Windows?
You need an Intel-based processor to run Windows at (or near) full speed. The Core 2 Duo and Xeon processors include special capabilities to run virtual operating systems.
While the older PowerPC processors (like the G4 or G5 computers) can run Windows using something like Microsoft's Virtual PC, anecdotal reports from users suggest a slow, frustrating experience. Because of the PowerPC's design, Virtual PC runs Windows in a processor-intensive, emulated environment. Development on Virtual PC for Mac OS X has ceased. Virtual PC is not recommended.
Dual-boot, guest OS, or remote session?
There are three primary ways you can use Windows on your Mac.
- Dual-boot generally means shutting down Mac OS X and restarting your computer into another operating system. Examples of this include Apple's Boot Camp.
- Guest OS (also called "virtualization") means running Windows as a guest operating system inside of Mac OS X (which is called the Host OS). It runs as a program. You can switch back and forth between Mac OS X and Windows, even dragging and dropping files between the two. Your Windows programs are contained within this virtual Windows environment. Software is needed to run a guest OS (for example, Parallels for Mac and VMWare Fusion).
- Remote session means you connect to a full-fledged PC somewhere over the network. Since you're not really running Windows on your own computer, we won't discuss this arrangement. You can read more about Remote Desktop for Mac OS X at Microsoft's Mactopia web site. Another arrangement is to use Citrix products, which are popular with large enterprise markets. VNC is an open source remote desktop solution.
Software options
Here are a few application options for running Windows on your Mac.
Boot Camp
This is a dual-boot Windows solution from Apple. Prior to the Leopard release, it was a "beta" release. It's currently a free download for Mac OS X 10.4, though you still need a license for Windows XP or Vista.
With Mac OS X v.10.5 (Leopard), Boot Camp became part of the operating system release.
Virtualization
Parallels for Mac is currently at version 3. It allows you to run Windows within Mac OS X. You can download the trial version, which will expire after a period of time. At any point, you can buy a serial number online to convert the trial version into a supported license. It costs about $80 for most users, with substantial discounts for multiple license packs. In addition to every edition of Windows, it can also host Linux, UNIX, Solaris, and other operating systems.
VMWare Fusion is very similar to Parallels. You can download the beta version and run any number of operating systems within Mac OS X.
Others
OnMac.net XOM is an open source alternative to Boot Camp. Released prior to Apple's debut of Boot Camp, it was the first native boot solution for Intel-based Macs. Development is still ongoing despite Boot Camp's success and the software is free.
CrossOver is unique in that it allows you to run Windows applications on your Mac without the need to install a Windows operating system (or a Windows license). It is built on Wine, which is an open source project with support mostly from Linux developers. Not all applications will run in the CrossOver, though many popular applications like Outlook and Quicken do. A single user license is about $60.
Wine is not yet fully supported on Mac OS X, though it remains an actively maintained project in the open source community. It is free.
Recommendations
For most users, running Windows as a virtualized, guest OS using Parallels is recommended. However, for some purposes, installing Windows using Boot Camp may produce a more satisfying Windows experience, especially with Vista or with games and other 3D graphics applications. If you plan to use your Mac primarily as a Windows station (rarely rebooting into Mac OS X) this may be the best choice. But there are serious drawbacks and risks (see the following list of considerations). And remember that Boot Camp is still beta software (until Leopard is released).
Special considerations
Hardware requirements
If running multiple operating systems appeals to you, you'll need to consider your Mac's hardware. You'll need a good amount of RAM to run two or more operating systems simultaneously. 2 GB of RAM should allow you to run both Mac OS X and Windows XP smoothly side-by-side.
With both Parallels or VMWare, you can experiment allocating RAM. Start by allowing around 1 GB (1024 MB) to the guest OS. If you're typically only using one simple application in Windows, try reducing the RAM allocation to 768 MB. This will free up RAM for your Mac. Conversely, if you are using many Windows applications simultaneously, Windows may warn you about low memory. Try increasing the guest OS RAM allocation to 1.25 GB (1280 MB). This will diminish your Mac's performance. Adjust the settings for optimal performance of both Mac OS X and Windows.
If you are using Boot Camp, you can only run one operating system at a time, so you don't need quite as much RAM. On the other hand, you may need more hard drive space, since Boot Camp will partition your disk to accommodate both operating systems. You decide at the time of installation how much space to give Windows, but if you underestimate, you'll have to reformat your drive. Be generous, but leave enough for growth.
Backup
Using two or more operating systems presents some challenges to backing up. You can either backup your computer from the Mac side of things, though this may not work with Boot Camp, or you can have multiple strategies, one for each guest operating system.
Mac-based solutions
Let's say you have a backup strategy in place on your Mac already. Typically, backup programs scan your hard drive for new or modified files, then back them up to tape or disk. If you use Parallels or VMWare Fusion frequently, you'll have a few gigantic files, some 8 GB or larger, being backed up every day. If you're being backed up over the network (or worse, the internet), or if the backup software tries to compress these files on-the-fly, you may find the experience exceptionally frustrating. You could exclude the guest OS files from your Mac's backup routine, but then you'd have twice the risk exposure. Issues with your Mac—or a virtualized Windows OS—could put your guest OS data at risk.
Windows-based solutions
If you are using Boot Camp, you may need an entirely different backup strategy. You may consider your Windows partition as a separate computer needing its own backup software. If you are booted into Mac OS X, your Windows machine won't be backed up, however, and vice versa. This makes unattended or automated backup uniquely difficult.
Networking, NetDB registration
Generally, virtual machines have virtual Ethernet hardware addresses. To use Parallels or VMWare on campus, those virtual MAC addresses need to be entered into NetDB for network connectivity. Even if you choose to use NAT (http://en.wikipedia.org/wiki/Network_address_translation) (or "Shared Networking" in Parallels) and your guest OS gets a private IP address (like 192.168.0.2) instead of a Stanford IP address (eg, 171.64.198.69), you won't be able to connect to the internet without first registering in NetDB. We recommend giving the virtual machine its own, new hostname entry, rather than adding the virtual MAC address under your host computer's NetDB entry.
If you are using Boot Camp, you do not need to modify NetDB (because Windows uses your Mac's real Ethernet hardware address, which presumably has already been entered).
Security issues
Viruses, spyware, and other Windows maladies
Your Windows OS will still need antivirus and anti-spyware software, regardless of whether it's virtualized with VMWare or Parallels, or installed using Boot Camp. Windows-based viruses and spyware will be contained in your Windows guest OS or partition and cannot spread to your Mac, but you should still use caution and consider installing antivirus software on your Mac, too, for possible future vulnerabilities.
You will also need to be diligent about keeping Windows updated using Microsoft Update. The same goes for any other guest OS, like Red Hat Enterprise Linux.
Special security concerns with Boot Camp
Boot Camp works by partitioning your hard drive and preparing it for a Windows installation. Because of this, any user who can log into your Mac will have access to the entire Windows partition, with no restrictions or security enforcement (beyond encrypting individual files). While it's possible to hack your Mac OS X system to obscure the Windows partition, such hacks may compromise overall stability.
If, during the installation procedure, you format your Windows partition as NTFS instead of FAT32, users will not be able to write to the Boot Camp partition (but they will be able to read any unencrypted file). Normal UNIX conventions for security such as permissions and access control lists (ACLs) are not applicable on these file systems.
Parallels and VMWare store your Windows virtual machines in your Mac's home directory, which is restricted with permissions and enforceable restrictions.
Licensing and other issues
Windows licensing
You must provide your own license for Windows. Generally, you cannot have the same copy of Windows installed more than once, and there are restrictions on activation.
Special Vista licensing considerations
Microsoft does not permit running Vista in any virtualization capacity except the Vista Business or Vista Ultimate editions.
Support for mathematical precision
While almost any Windows application will run under VMWare, Parallels, or Boot Camp, some software publishers will not support this because of the requirement for extreme scientific precision. For example, SPSS is not supported under any virtualization or emulation scheme as expressed on their web site. This includes booting into Windows on a Mac. If you are using these types of programs, be sure to visit the manufacturers web site for information first.
Running Mac OS X inside Windows
It's presumed technically possible, though it's probably illegal. No reputable commercial program provides this capability (and all Apple licenses expressly forbid it).
If you have a question about running a Windows OS on your Macintosh that is not covered here, please submit a HelpSU ticket.
