Running windows in Mac OS X

In a cross-platform world, it pays to be able to run Windows on your Mac. While you can’t do this completely for free — you’ll have to shell out for a licensed copy of Windows — you don’t have to pay for the Mac software that runs Windows.

Boot Camp
Apple’s Boot Camp is dual-boot software that’s included with today’s Intel-based Macs. Boot Camp allows users to partition their hard drives into separate Mac and Windows volumes and install Windows XP or Vista. The catch is that you can’t run Mac OS X and Windows simultaneously.

VirtualBox

Virtualization software, on the other hand, allows Windows to run alongside Mac OS X as a guest OS in a virtual PC. Sun’s open-source VirtualBox offers roughly the same core feature set as commercial virtualization software such as Parallels Desktop and VMWare Fusion. Some add-on features aren’t matched, but VirtualBox is a solid program that comes at no cost. Installation is also generally simple and straightforward.