See 's Virtualization Benchmarking for comparisons of Boot Camp, Parallels, and VM Fusion. The latter tend to be a little slower (not much) and do not provide the video performance of the dual-boot system. There are performance differences between dual-boot systems and virtualization. Note that Parallels and VM Fusion can also run other operating systems such as Linux, Unix, OS/2, Solaris, etc. It is not as fully developed for the Mac as Parallels and VM Fusion. VirtualBox is a new Open Source freeware virtual machine such as VM Fusion and Parallels that was developed by Solaris.The Windows applications can run concurrently with OS X. CrossOver which enables running many Windows applications without having to install Windows.VM Fusion is software virtualization that enables running Windows concurrently with OS X. VM Fusionand Windows XP, Vista Business, Vista Ultimate, or Windows 7.Parallels is software virtualization that enables running Windows concurrently with OS X. Parallels Desktop for Mac and Windows XP, Vista Business, Vista Ultimate, or Windows 7.

Boot Camp enables you to boot the computer into OS X or Windows. Follow instructions in the Boot Camp documentation on installation of Boot Camp, creating Driver CD, and installing Windows. There are presently several alternatives for running Windows on Intel Macs.

You can run Windows on a Mac, but how and what depends on the Mac model.

Run windows programs on mac